Fix documentation of std.digest.ripemd

Fixes the broken link to the source file and beautifies the reference list.
Merge pull request #1242 from redstar/ripedoc

Fix documentation of std.digest.ripemd
fix Issue 9836 - std.array.popFront does not work with alias this.

empty, front, popFront, back, popBack should work with alias this type.
Merge pull request #1233 from 9rnsr/fix9836

Issue 9836 - std.array.popFront does not work with alias this.