[PR] Fix markdown typo
[PR] Fix markdown typo

Summary:
This fixes a typo in the documentation where there is an extra `*` at the end of an ***italicised bold*** sentence which seems to suggest there is more information on the subject! but it's just a typo!!!

Anyway, I fixed it for you :)
Closes https://github.com/facebook/flow/pull/5484

Reviewed By: gabelevi

Differential Revision: D6539118

Pulled By: calebmer

fbshipit-source-id: c0a4ba5e74cc808f6f554ab95c65830158cb45cb

AgentME/flow,nmote/flow,nmote/flow,claudiopro/flow,samwgoldman/flow,popham/flow,jamesgpearce/flow,gabelevi/flow,gabelevi/flow,facebook/flow,facebook/flow,claudiopro/flow,jamesgpearce/flow,samwgoldman/flow,nmote/flow,claudiopro/flow,jamesgpearce/flow,JonathanUsername/flow,jamesgpearce/flow,facebook/flow,JonathanUsername/flow,JonathanUsername/flow,facebook/flow,jamesgpearce/flow,gabelevi/flow,AgentME/flow,mroch/flow,jamesgpearce/flow,jamesgpearce/flow,samwgoldman/flow,popham/flow,mroch/flow,popham/flow,samwgoldman/flow,mroch/flow,gabelevi/flow,popham/flow,nmote/flow,popham/flow,mroch/flow,nmote/flow,popham/flow,AgentME/flow,nmote/flow,samwgoldman/flow,nmote/flow,AgentME/flow,JonathanUsername/flow,samwgoldman/flow,facebook/flow,mroch/flow,facebook/flow,JonathanUsername/flow,claudiopro/flow,JonathanUsername/flow,mroch/flow,gabelevi/flow,gabelevi/flow,facebook/flow,mroch/flow,samwgoldman/flow,gabelevi/flow,claudiopro/flow,popham/flow,JonathanUsername/flow,AgentME/flow