revise weaveDNS docs
revise weaveDNS docs

- add ToC and anchors for all headings
- move docker bridge settings into "How it works" - it's a rarely used
  feature
- highlight a bunch of features, extracting them from obscurely titled
  sub-sections of "manual usage"
  - basic rendundancy
  - adding/removing extra DNS entries
  - service hot-swapping
  - ability to retain entries for stopped containers
  - using a different local domain
- rename remainder of "manual usage" section to "Using weaveDNS
  without `weave run`"
- remove "Unregistering" section - it was out of date and is not
  covered by the "add/remove" section

weaveworks/weave,aaam/weave,OnePaaS/weave,squaremo/weave,ycaihua/weave,narry/weave,aaam/weave,achanda/weave,awh/weave,dpw/weave,2opremio/weave,paulbellamy/weave,cgvarela/weave,dpw/weave,2opremio/weave,rade/weave,achanda/weave,awh/weave,paulbellamy/weave,dpw/weave,ycaihua/weave,cgvarela/weave,OnePaaS/weave,tomwilkie/weave,bboreham/weave,philipz/weave,inercia/weave,paladin74/weave,awh/weave,errordeveloper/weave,ycaihua/weave,paladin74/weave,narry/weave,inercia/weave,squaremo/weave,squaremo/weave,awh/weave,awanke/weave,squaremo/weave,weaveworks/weave,bboreham/weave,rade/weave,tomwilkie/weave,rade/weave,ycaihua/weave,OnePaaS/weave,n054/weave,bboreham/weave,weaveworks/weave,kidaa/weave,errordeveloper/weave,aaam/weave,kidaa/weave,cgvarela/weave,BWITS/weave,cgvarela/weave,OnePaaS/weave,BWITS/weave,paulbellamy/weave,achanda/weave,errordeveloper/weave,aaam/weave,awh/weave,awanke/weave,dpw/weave,achanda/weave,awanke/weave,n054/weave,philipz/weave,paladin74/weave,kidaa/weave,BWITS/weave,tomwilkie/weave,errordeveloper/weave,philipz/weave,awanke/weave,narry/weave,beni55/weave,n054/weave,inercia/weave,BWITS/weave,kidaa/weave,beni55/weave,cgvarela/weave,beni55/weave,paladin74/weave,n054/weave,paladin74/weave,narry/weave,tomwilkie/weave,inercia/weave,inercia/weave,paulbellamy/weave,rade/weave,BWITS/weave,awanke/weave,OnePaaS/weave,philipz/weave,tomwilkie/weave,bboreham/weave,kidaa/weave,philipz/weave,beni55/weave,beni55/weave,errordeveloper/weave,dpw/weave,bboreham/weave,rade/weave,aaam/weave,narry/weave,weaveworks/weave,n054/weave,2opremio/weave,2opremio/weave,achanda/weave,ycaihua/weave,2opremio/weave,squaremo/weave