Add specs for files and merges request for main pull requests api.
Add specs for files and merges request for main pull requests api.

piotrmurach/github,joshsoftware/github,MalachiTatum/github,peter-murach/github,durai145/github,wicky-info/github,anabhilash619/github,cocktail-io/github,firstval/github,samphilipd/github,GistBox/github,davengeo/github,yaoxiaoyong/github,befairyliu/github