Content pages like `tutorial/index.md` were being mapped to `tutorial.index.json`,
which meant that they could only be rendered if you browsed to `/tutorial/index`.
This didn't sit well so now these pages are mapped to `tutorial.json`, which
means that you browser to them via `/tutorial/` or just `/tutorial`.
Fixed#15335
Implemented style guide elements to top header bar, side hamburger nav menu, content and search. Consolidated SCSS files to styles folder. Fixed PWA test.
All the docs related files (docs-app, doc-gen, content, etc)
are now to be found inside the `/aio` folder.
The related gulp tasks have been moved from the top level
gulp file to a new one inside the `/aio` folder.
The structure of the `/aio` folder now looks like:
```
/aio/
build/ # gulp tasks
content/ #MARKDOWN FILES for devguides, cheatsheet, etc
devguides/
cheatsheets/
transforms/ #dgeni packages, templates, etc
src/
app/
assets/
content/ #HTML + JSON build artifacts produced by dgeni from /aio/content.
#This dir is .gitignored-ed
e2e/ #protractor tests for the doc viewer app
node_modules/ #dependencies for both the doc viewer builds and the dgeni stuff
#This dir is .gitignored-ed
gulpfile.js #Tasks for generating docs and building & deploying the doc viewer
```
Closes#14361
Pete Bacon Darwin
Stefanie Fluin
Ward Bell
George Kalpakas