Adjusted the docs structure according to directives

Adjusted the docs structure according to directives

Created a new subdirectory /installationprocedure.
Moved the featureconfig.rst and installerconfig.rst to /installationprocedure
Added a feature.configuration.rst that should include needed configuration instructions. Please move relevant content to this file and remove the other two (featureconfig.rst and installerconfig.rst)
Index file adjusted to updates

Change-Id: I54f30b358b4e0685ff98223b1c83c14745c9259b
Signed-off-by: Sofia Wallin <sofia.wallin@ericsson.com>
(cherry picked from commit 5298fb1f996ab547c518b085e8c39fc5e0665bd9)