doc: deploying.rst improvement

- ReST syntax improvement (blockquote)
- suggest to rename config.json to local.json
  As adviced in I3129bf638e519f2b03a05cae482e26fd5aef40b1, the user
  should avoid changes in config.json, but use local.json instead.
- use local-config and stackuser element for bootstrap.qcow
- suggest the user of DIB_IMAGE_SIZE=30 env var

Change-Id: Ifc8672907a9b155273deda55cce80d3f5323ea47
Rest syntax fixes

Change-Id: I8b70f5d02db3a71fa49809ef060b4a9eadca78d8
Merge "doc: deploying.rst improvement"
Merge "Rest syntax fixes"