Remove various outdated documents.

doc/TODO and doc/spec/README were placeholders to tell people where to
look for the real TODO and README stuff -- we replaced them years ago,
though.

authority-policy, v3-authority-howto, and torel-design.txt belong in
torspec.  I'm putting them in attic there since I think they may be in
large part obsolete, but someone can rescue them if they're not.

translations.txt is outdated, and refers to lots of programs other
than Tor.  We have much better translation resources on the website
now.

tor-win32-mingw-creation.txt is pending review of a revised version
for 0.2.5 (see ticket #4520), but there's no reason to ship this one
while we're waiting for an accurate version.

the tor-rpm-creation.txt isn't obsolete AFAIK, but it belongs in
doc/contrib if anywhere.

Resolves bug #8965.
Fix the biggest errors in doc/HACKING

We can wait for 0.2.5 for a full rewrite.  #8964