[thread.threads] Indent members of namespace this_thread.

Fixes #66
[unord.req] Fix "load load factor" typo.
Merge pull request #87 from FrankHB/patch-1

[unord.req] Fix "load load factor" typo.

Fixes #85 too
[adjacent.difference] Add missing paragraph number.

Reported by Stephan T. Lavavej.

Fixes #84