Document authx feature, Phases I and II

user-guide
- cli.rst -- document fuel cli command to change
  password and flags to use with commands to supply password;
  fixed a couple typos while the file was open
- initialize-fuel/0400-pxe-config.rst -- added screen shot
  for setting password during Fuel Setup
- create-environment/1000-start-create-env.rst
  - Added Fuel login screen
  - Replaced initial Fuel screen to have "password" link showing
  - Added text and screen shot for modifying password

ops-guide -- 6500-fuel-auth -- explain authorization functionality

release-notes -- 020-new-features -- added link to ops guide info,
which includes links to the other docs

terminology -- updated keystone article to point to password stuff

Change-Id: I6d2c515b6200be2307bf78b6c0a202e958d51220
Closes-Bug: 1348750