[9fans] sources/contrib index

[Uriel <uriell@binarydream.org>]

An index of the contents of sources/contrib and sources/extra can be
found in the wiki [Contrib index] page[1].

All directories in sources/contrib are indexed automatically, to add
comments to the contents of your contrib dir create an INDEX file with
entries of the format:

filename: Description

By default only the top directory is listed, but sub directories are
indexed if they contain an INDEX file.

The INDEX is rebuilt once a day with the script in
sources/contrib/uriel/contrindx

Also thanks to 20h we now have a full mirror of all sources/ which is
accessible over http[2](and 9p for 9grid.de users). Nashi and nemo have
mentioned they intend to setup more mirrors. For instructions about how
to setup a sources/ mirror see the [Mirrors] wiki page[3].

Again remind everyone to please upload your plan9-related software to
sources/contrib so it's easier to find software packages, and nothing
gets lost. That way your code will get mirrored automatically too.

[1] http://plan9.bell-labs.com/wiki/plan9/Contrib_Index/
[2] http://www.9grid.de/magic/webls?dir=/sources
[3] http://plan9.bell-labs.com/wiki/plan9/Mirrors/