Repos that use `readme.md` do not render the overview correctly

[fiveisprime]

The name of the file is hardcoded as README.md here:

ServerlessLibrary/ServerlessLibraryAPI/ClientApp/src/services/github.service.js

Line 22 in 2193e51

const readMeUrl = getRawContentUrl(repoUrl, "README.md");

This means any repo that uses readme.md won't show the overview page. For example: https://serverlesslibrary.net/sample/0409840c-b836-4095-8500-c57e0fa81168