Add notes about pre-release and string freeze
Getting a list of contributors
We don't support 2.5 anymore
Require at least toolkit 1.11.0
Seems pip does understand rc1 versions
Link to placeables spec
Use -- for emdash
Cleanups
Docs: Removed hacking instructions for impatients

You should be patient and follow all the steps to avoid fucking it.
Docs: Cleanups and minor fixes in hacking docs

* Using the correct markup,
* Adding blank lines,
* Rephrasing some text,
* Adding some sample commands,
* Other changes.
Docs: Added more content to commiting section in hacking docs
Docs: Make switch virtualenv instructions more prominent

Converted instructions to switch the virtualenv on and off to a note with
examples. This way is more difficult to miss it.