Added the redirect of programming-guide.html to rdd-programming-guide.html for 2.2.0 docs

[tdas]

This was generated by copying the programming-guide.md from branch-2.2 to the commit tagged v2.2.0.
So it should not touch anything else. This should automatically redirect any attempt to access programming-guide.html to rdd-programming-guide.html.

[tdas]

@srowen @marmbrus

[srowen]

Sure, looks good as a patch. The main site (outside docs/) already doesn't point to this file, but of course the 2.2.0 docs do, so this is good as a hotfix. We can consider just pulling the redirect or else fixing it in the spark repo docs later.