Recommend use of PYTHONHASHSEED

[Jacob]

Our documentation - probably the deployment checklist? - should strongly recommend the use of -R/PYTHONHASHSEED.

[Ryan Kaskel]

I've created a first draft here: ​https://github.com/ryankask/django/commit/add86762abf3d8c5adf85e427df1dde46c8716b3

A few notes:

• I put it at the bottom of the deployment checklist because the rest of the document deals with Django settings as opposed to Python options/settings. I don't know if that's the sort of visibility you intended
• It's only available in 2.6.8+ and we currently support 2.6.5+ -- not that big a deal I don't think
• If you happen to rely on the ordering of keys of a dict, this will probably break that. Should we mention this in the note?
• I can't figure out how to link to the option in the Python docs using InterSphinx. :python:option:`-R` doesn't work. Should I just use a normal link?

Any other feedback is much appreciated. I didn't know about this option and I was glad I read about it.

[Tim Graham]

Looks good. I tried a bit and couldn't get the -R link to work either so I've just added a normal link, will commit shortly.

[Tim Graham <timograham@…>]

In 8aca2504df9d7d3c1244d1632f6cad45afa60115:

Fixed #20080 - Recommended use of PYTHONHASHSEED

Thanks jacob for the suggestion and ryankask
for the patch.