docs: added maintainer documentation with FileSystemWatcherMock#928

vbreuss merged 3 commits intoTestably:mainTestably/Testably.Abstractions:mainfrom

pw-sgr:926-docs-add-markdown-file-for-filesystemwatchermockpw-sgr/Testably.Abstractions:926-docs-add-markdown-file-for-filesystemwatchermockCopy head branch name to clipboard