Squashed commit of the following:

commit 3ddc5e522969d8e5270dc408eec71fc0847c40ce
Author: Lucas Parsy <lucas.parsy@nexedi.com>
Date:   Thu Dec 17 16:44:19 2015 +0100

    corrected misspellings and ambiguous examples in manage_document file.
    deleted gid and revision storage documentation.

commit 85d30999afdd227c8d4085fcd2df329f0d95333e
Author: Lucas Parsy <lucas.parsy@nexedi.com>
Date:   Tue Dec 15 15:13:23 2015 +0100

    updated documentation
    renamed "revision_storage.rst" "replicate_storage.rst"
    you need to "compile" the files (go in doc/ directory and type "make")
    to have the html files.