Merge pull request #1607 from ahoppen/move-background-indexing-doc

Move `Background Indexing.md` to `Contributor Documentation`

Author: ahoppen

Documentation/Background Indexing.md renamed to Contributor Documentation/Background Indexing.md

@@ -2,6 +2,7 @@
 
 The following documentation documents are primarily intended for developers of SourceKit-LSP.
 
+- [Background Indexing](Background%20Indexing.md)
 - [Files To Reindex](Files%20To%20Reindex.md)
 - [LSP Extensions](LSP%20Extensions.md)
 - [Logging](Logging.md)