This commit adds documentation and tests for the 'flush' option
of the fs.appendFile family of functions. Technically, support
was indirectly added in #50009, but this makes it more official.
Refs: #49886
Refs: #50009
PR-URL: #50095
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

Notable changes:
doc:
  * add H4ad to collaborators (Vinícius Lourenço) #50217
esm:
  * (SEMVER-MINOR) detect ESM syntax in ambiguous JavaScript (Geoffrey Booth) #50096
fs:
  * (SEMVER-MINOR) add flush option to appendFile() functions (Colin Ihrig) #50095
lib:
  * (SEMVER-MINOR) add `navigator.userAgent` (Yagiz Nizipli) #50200
stream:
  * (SEMVER-MINOR) allow pass stream class to `stream.compose` (Alex Yang) #50187
  * call helper function from push and unshift (Raz Luvaton) #50173
PR-URL: #50335

Notable changes:
doc:
  * add H4ad to collaborators (Vinícius Lourenço) #50217
esm:
  * (SEMVER-MINOR) detect ESM syntax in ambiguous JavaScript (Geoffrey Booth) #50096
fs:
  * (SEMVER-MINOR) add flush option to appendFile() functions (Colin Ihrig) #50095
lib:
  * (SEMVER-MINOR) add `navigator.userAgent` (Yagiz Nizipli) #50200
stream:
  * (SEMVER-MINOR) allow pass stream class to `stream.compose` (Alex Yang) #50187
  * call helper function from push and unshift (Raz Luvaton) #50173
PR-URL: #50335

Notable changes:
doc:
  * add H4ad to collaborators (Vinícius Lourenço) #50217
esm:
  * (SEMVER-MINOR) detect ESM syntax in ambiguous JavaScript (Geoffrey Booth) #50096
fs:
  * (SEMVER-MINOR) add flush option to appendFile() functions (Colin Ihrig) #50095
lib:
  * (SEMVER-MINOR) add `navigator.userAgent` (Yagiz Nizipli) #50200
stream:
  * (SEMVER-MINOR) allow pass stream class to `stream.compose` (Alex Yang) #50187
  * call helper function from push and unshift (Raz Luvaton) #50173
PR-URL: #50335

Notable changes:
doc:
  * add H4ad to collaborators (Vinícius Lourenço) #50217
esm:
  * (SEMVER-MINOR) detect ESM syntax in ambiguous JavaScript (Geoffrey Booth) #50096
fs:
  * (SEMVER-MINOR) add flush option to appendFile() functions (Colin Ihrig) #50095
lib:
  * (SEMVER-MINOR) add `navigator.userAgent` (Yagiz Nizipli) #50200
stream:
  * (SEMVER-MINOR) allow pass stream class to `stream.compose` (Alex Yang) #50187
  * call helper function from push and unshift (Raz Luvaton) #50173
PR-URL: #50335

This commit adds documentation and tests for the 'flush' option
of the fs.appendFile family of functions. Technically, support
was indirectly added in #50009, but this makes it more official.
Refs: #49886
Refs: #50009
PR-URL: #50095
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

Notable changes:
deps:
  * (SEMVER-MINOR) update uvwasi to 0.0.19 (Node.js GitHub Bot) #49908
doc:
  * add H4ad to collaborators (Vinícius Lourenço) #50217
esm:
  * (SEMVER-MINOR) detect ESM syntax in ambiguous JavaScript (Geoffrey Booth) #50096
  * use import attributes instead of import assertions (Antoine du Hamel) #50140
  * --experimental-default-type flag to flip module defaults (Geoffrey Booth) #49869
fs:
  * (SEMVER-MINOR) add flush option to appendFile() functions (Colin Ihrig) #50095
  * add flush option to writeFile() functions (Colin Ihrig) #50009
lib:
  * (SEMVER-MINOR) add WebSocket client (Matthew Aitken) #49830
stream:
  * (SEMVER-MINOR) allow pass stream class to `stream.compose` (Alex Yang) #50187
  * call helper function from push and unshift (Raz Luvaton) #50173
  * optimize Writable (Robert Nagy) #50012
test_runner, cli:
  * (SEMVER-MINOR) add --test-concurrency flag (Colin Ihrig) #49996
vm:
  * (SEMVER-MINOR) use import attributes instead of import assertions (Antoine du Hamel) #50141
  * use default HDO when importModuleDynamically is not set (Joyee Cheung) #49950
wasi:
PR-URL: #50682

Notable changes:
deps:
  * (SEMVER-MINOR) update uvwasi to 0.0.19 (Node.js GitHub Bot) #49908
doc:
  * add H4ad to collaborators (Vinícius Lourenço) #50217
esm:
  * (SEMVER-MINOR) detect ESM syntax in ambiguous JavaScript (Geoffrey Booth) #50096
  * use import attributes instead of import assertions (Antoine du Hamel) #50140
  * --experimental-default-type flag to flip module defaults (Geoffrey Booth) #49869
fs:
  * (SEMVER-MINOR) add flush option to appendFile() functions (Colin Ihrig) #50095
  * add flush option to writeFile() functions (Colin Ihrig) #50009
lib:
  * (SEMVER-MINOR) add WebSocket client (Matthew Aitken) #49830
stream:
  * (SEMVER-MINOR) allow pass stream class to `stream.compose` (Alex Yang) #50187
  * call helper function from push and unshift (Raz Luvaton) #50173
  * optimize Writable (Robert Nagy) #50012
test_runner, cli:
  * (SEMVER-MINOR) add --test-concurrency flag (Colin Ihrig) #49996
vm:
  * (SEMVER-MINOR) use import attributes instead of import assertions (Antoine du Hamel) #50141
  * use default HDO when importModuleDynamically is not set (Joyee Cheung) #49950
wasi:
PR-URL: #50682

Notable changes:
deps:
  * (SEMVER-MINOR) update uvwasi to 0.0.19 (Node.js GitHub Bot) #49908
doc:
  * add H4ad to collaborators (Vinícius Lourenço) #50217
esm:
  * (SEMVER-MINOR) detect ESM syntax in ambiguous JavaScript (Geoffrey Booth) #50096
  * use import attributes instead of import assertions (Antoine du Hamel) #50140
  * --experimental-default-type flag to flip module defaults (Geoffrey Booth) #49869
fs:
  * (SEMVER-MINOR) add flush option to appendFile() functions (Colin Ihrig) #50095
  * add flush option to writeFile() functions (Colin Ihrig) #50009
lib:
  * (SEMVER-MINOR) add WebSocket client (Matthew Aitken) #49830
stream:
  * (SEMVER-MINOR) allow pass stream class to `stream.compose` (Alex Yang) #50187
  * call helper function from push and unshift (Raz Luvaton) #50173
  * optimize Writable (Robert Nagy) #50012
test_runner, cli:
  * (SEMVER-MINOR) add --test-concurrency flag (Colin Ihrig) #49996
vm:
  * (SEMVER-MINOR) use import attributes instead of import assertions (Antoine du Hamel) #50141
  * use default HDO when importModuleDynamically is not set (Joyee Cheung) #49950
wasi:
PR-URL: #50682

Notable changes:
deps:
  * (SEMVER-MINOR) update uvwasi to 0.0.19 (Node.js GitHub Bot) nodejs#49908
doc:
  * add H4ad to collaborators (Vinícius Lourenço) nodejs#50217
esm:
  * (SEMVER-MINOR) detect ESM syntax in ambiguous JavaScript (Geoffrey Booth) nodejs#50096
  * use import attributes instead of import assertions (Antoine du Hamel) nodejs#50140
  * --experimental-default-type flag to flip module defaults (Geoffrey Booth) nodejs#49869
fs:
  * (SEMVER-MINOR) add flush option to appendFile() functions (Colin Ihrig) nodejs#50095
  * add flush option to writeFile() functions (Colin Ihrig) nodejs#50009
lib:
  * (SEMVER-MINOR) add WebSocket client (Matthew Aitken) nodejs#49830
stream:
  * (SEMVER-MINOR) allow pass stream class to `stream.compose` (Alex Yang) nodejs#50187
  * call helper function from push and unshift (Raz Luvaton) nodejs#50173
  * optimize Writable (Robert Nagy) nodejs#50012
test_runner, cli:
  * (SEMVER-MINOR) add --test-concurrency flag (Colin Ihrig) nodejs#49996
vm:
  * (SEMVER-MINOR) use import attributes instead of import assertions (Antoine du Hamel) nodejs#50141
  * use default HDO when importModuleDynamically is not set (Joyee Cheung) nodejs#49950
wasi:
PR-URL: nodejs#50682