#555 [doc] decrypt_headers.php took 20 minutes to find

[peter gervai]

The documentation regarding decrypting encrypted headers ( X-Squirrel-UserHash: and X-Squirrel-FromHash: ) is at best sparse, and I may dare to call it even non-existant. Google search for the mentioned headers come up with nothing and only a full grep of the whole source came up with conf.pl which mentioned decrypt_headers.php, which accidentally not in Debian default packaging.
This tidbit should be mentioned a few places, like $encode_header_key documentation. I found it, so it's for the better future, for others.