docs: Add upgrade instructions
docs: Add upgrade instructions

Fixes #229.

lcnature/brainiak,CameronTEllis/brainiak,TuKo/brainiak,lcnature/brainiak,yidawang/brainiak,TuKo/brainiak,TuKo/brainiak,mihaic/brainiak,IntelPNI/brainiak,brainiak/brainiak,yidawang/brainiak,mihaic/brainiak,IntelPNI/brainiak,CameronTEllis/brainiak,IntelPNI/brainiak,CameronTEllis/brainiak,lcnature/brainiak,brainiak/brainiak,brainiak/brainiak,yidawang/brainiak,mihaic/brainiak