RT1941: c_rehash.pod is missing

Add the file written by James Westby, graciously contributed
under the terms of the OpenSSL license.

Reviewed-by: Andy Polyakov <appro@openssl.org>
RT2379: Additional typo fix

Andy found an additional typo "can be can be".
Now I have that silly "Que sera sera" song stuck in my head.

Reviewed-by: Andy Polyakov <appro@openssl.org>
RT2119,3407: Updated to dgst.pod

Re-order algorithm list.
Be consistent in command synopsis.
Add content about signing.
Add EXAMPLE section
Add some missing options: -r, -fips-fingerprint -non-fips-allow
Various other fixes.

Reviewed-by: Andy Polyakov <appro@openssl.org>
RT2820: case-insensitive filenames on Darwin

Andy pointed out there is also darwin64, so tweak the pattern.

Reviewed-by: Andy Polyakov <appro@openssl.org>
Remove some outdated README files, to avoid confusing people.

Reviewed-by: Andy Polyakov <appro@openssl.org>