Add framework code space usage to docs

[blindman2k]

It would be good to provide some idea of the current code-space usage of the framework. In other words we should publish how much of your code space must be available to install the framework. It is probably best presented in the README.md as a percentage of code space, possibly for each imp type (imp-001/2, imp-003).

[myurasov]

Good idea. Current number is roughly 12.97% on 001 (incl. 0.45% blank firmware takes).