Tidy up docs directory

[russcam]

Tidy up the docs directory to avoid confusion

• delete everything but the contents of asciidoc and 2.0-breaking-changes in master
• delete everything but the contents of asciidoc and 2.0-breaking-changes in 2.x
• delete everything but the contents of asciidoc in 1.x
• move the contents of asciidoc and 2.0-breaking-changes under docs directly

[russcam]

Moved docs to root of doc directory in

• master: 3755235
• 2.x: 02d1547
• 1.x: d23ad5b