Readme.md updates from PR feedback
Readme.md updates from PR feedback

Correct section numbering.
Provide symbol output examples.
Add statement separate and statement continuation syntax.
Move built-in functions under expression parser section.
Update list of built-in MIPS macros.
Move change log and migration to end of document.

sp1187/armips,Kingcom/armips,sp1187/armips,Kingcom/armips,Kingcom/armips,hrydgard/armips,sp1187/armips,hrydgard/armips,hrydgard/armips