Prettified all HTML files

Prettified all HTML files using Beautiful Soup with the
following script.

https://github.com/berendt/openstack-development/blob/master/prettify.py

Change-Id: Iee7cefce73769cea393b891bd0b01e484e767014
Fix wrong URLs of default security group rules management

1. 'os-security-group-rules' in the URLs should be
'os-security-group-default-rules';
2. add guide for deleting default security group rule

Change-Id: I11bf1d88182a5117da1d89696f03552c4131def6
Closes-bug: #1326950
Merge "Fix wrong URLs of default security group rules management"