Excluding specific file names and types (not categories, not folders) from Spotlight
I am the developer of HoudahSpot, a file search utility that uses the Spotlight index. 

I don’t know of a way to teach the Spotlight interface to skip certain files. Nor do I know a way to get the Spotlight indexer to exclude files by name.

In HoudahSpot you can add criteria to exclude files whose names contain readme or faq or have the php file extension. You can then make this search your default setup. Your HoudahSpot searches will always start with these exclusions.