Create developer-notes.md

Moves coding guidelines and development tips/tricks into a single file.
Also adds a section explaining pull request terminology.

doc/README.md

@@ -51,7 +51,7 @@ Development
 ---------------------
 The Bitcoin repo's [root README](https://github.com/bitcoin/bitcoin/blob/master/README.md) contains relevant information on the development process and automated testing.
 
-- [Coding Guidelines](coding.md)
+- [Developer Notes](developer-notes.md)
 - [Multiwallet Qt Development](multiwallet-qt.md)
 - [Release Notes](release-notes.md)
 - [Release Process](release-process.md)