watchman: add main page (#16424)

Co-authored-by: Managor <42655600+Managor@users.noreply.github.com>

pages/common/watchman.md

@@ -0,0 +1,28 @@
+# watchman
+
+> A service that watches files, and triggers actions when changes occur.
+> More information: <https://facebook.github.io/watchman/docs/cli-options>.
+
+- Start watching a directory for changes:
+
+`watchman watch {{path/to/directory}}`
+
+- Add a trigger to run a command when files with a specified filename pattern in a watched directory change:
+
+`watchman -- trigger {{path/to/watched_directory}} {{trigger_name}} '{{pattern}}' -- {{command}}`
+
+- List all watched directories:
+
+`watchman watch-list`
+
+- Delete a watch on a directory:
+
+`watchman watch-del {{path/to/watched_directory}}`
+
+- List all triggers on a watched directory:
+
+`watchman trigger-list {{path/to/watched_directory}}`
+
+- Delete a trigger from a watched directory:
+
+`watchman trigger-del {{path/to/watched_directory}} {{trigger_name}}`