Issue 5333 - Allow cms to generate relative pages

docs/usage/generate-static-files.md

 # Generating static files #
 
 On your production server you should convert the content directory into static
 files. To do that you need:
 
 * Python 2.7
 * [Jinja2](http://jinja.pocoo.org/) and
   [Markdown](https://pypi.python.org/pypi/Markdown) modules (can be installed by
   running `easy_install Jinja2 Markdown` from the command line)
 * A current copy of the
   [cms repository](https://github.com/adblockplus/cms/) (can be
   [downloaded as ZIP file](https://github.com/adblockplus/cms/archive/master.zip)
   or cloned via `git clone https://github.com/adblockplus/cms.git`)
 
 Run the following command from the directory of the `cms` repository:
 
     python -m cms.bin.generate_static_pages www_directory target_directory
 
 Here `www_directory` should be replaced by the path to your content directory.
 `target_directory` is the path where static files will be placed.
 
+The files can also be generated with relative links instead of asolute links by
+using the `--relative` option:
+
+    python -m cms.bin.generate_static_pages www_directory target_directory --relative
+
 Note: Localized versions of pages will only be generated when their translations
 are at least 30% complete. (Measured by comparing the total number
 of translatable strings on a page to the number of strings that have been
 translated for a given locale.) This is different from the test server which
 will include less complete translations.