Make EV charging Implementation guide v0.8 easy to navigate

[ameetdesh]

• Added an expandable table of contents.

• Updated the context.jsonld in json example to point to v2 location. (branch name in the path is still draft, which will need to be modified later.)
• Changed indents on various sub-sub sections to make logical sense regard hierarchy.
• Made all json examples expandable to reduce visual clutter when someone browses the doc for the first time.
• Made the links to the specific example json files on github relative, so that they would work in any branch, and do not need to be changed.

To see a preview of rendered markdown with table of contents and expand blocks, see here.

[ravi-prakash-v]

Looks good @ameetdesh