Update local development instructions

Moved from GitHub ratel/90

Posted by martinmr:

Build instructions are not accurate.

paulftw commented :

Can you please be more specific?
readme doesn’t actually have any build instructions to start with

martinmr commented :

It’s on INSTRUCTIONS.md, sorry. The local development section is inaccurate since the build.local.sh script does not exist.

paulftw commented :

67cc8999019908adf3f816f5b3e73d606f7013cc

Animesh told me he could build ratel following current instructions