pg_createsubscriber: add page

[chitvs]

• The page(s) are in the correct platform directories: common, linux, osx, windows, sunos, android, etc.
• The page description(s) have links to documentation or a homepage.
• The page(s) follow the content guidelines.
• The page(s) follow the style guide.
• The PR contains at most 5 new pages.
• The PR title conforms to the recommended templates.
• Version of the command being documented (if known):

[tldr-bot]

The build for this PR failed with the following error(s) at commit
d384c40f66aa154012849dfed7f75e0103259f18:

pages/common/pg_createsubscriber.md:24:37 MD047/single-trailing-newline Files should end with a single newline character
pages/common/pg_createsubscriber.md:1: TLDR009 Page should contain a newline at end of file

Please fix the error(s) and push again.