Brigade: Improve documentation

[radu-matei]

This issue tracks the re-vamping of the documentation for Brigade - specifically, clean sections for user guide, coding reference, admin guide.

related: #748, #79, #314, #450, #451. #506, #595

TODO

• [x] topics navigation - https://github.com/Azure/brigade/pull/782
• [x] update (or ensure content covered and remove) docs/topics/install.md - https://github.com/Azure/brigade/pull/783
• [x] remove "experimental" mentions -> https://github.com/Azure/brigade/pull/791
• [x] #79 -> https://github.com/Azure/brigade/pull/784
• [x] #314 -> https://github.com/Azure/brigade/pull/785
• [x] #450
• [x] #451 -> https://github.com/Azure/brigade/pull/791
• [x] Update references around Brigade project install/upgrade to use brig cli as opposed to (deprecated) Helm chart approach -> https://github.com/Azure/brigade/pull/794

(TODO list added by vdice 1/23/19; last edited 1/31/19)

[dgkanatsios]

One thing that I think should be fixed is the navigation in topics. As soon as I visit any page, e.g. this, there is no easy way to return to the table of contents unless I use browser's back button.

[vdice]

I'll take this one on. As the description is fairly far-reaching, I'll start to ensure all of the referenced tickets are covered, as well as the note from @dgkanatsios and then put up a PR...

[radu-matei]

Question: currently, the landing page is on one domain (brigade.sh), while the documentation is directly on GitHub Pages - would it make sense to move the docs under docs.brigade.sh?

If so, I'll add an item on the list.
Thanks!

[vdice]

We're getting close!! Added @radu-matei as an asignee as I believe he's cooking up docs around remote/local js module use.

[radu-matei]

Yes!!
Thanks a lot, everyone!

And particularly, thanks to @vdice, who has been absolutely fantastic working on docs last few weeks.