In #14388 the following syntax is used in the source:
```
import * as view_utils from './linker/view_utils';
import * as viewEngine from './view/index';
…
export {view_utils as ɵview_utils};
export {viewEngine as ɵviewEngine};
```
The usage of `export {... as ...}` was not being recognised by dgeni.
It is now being recognised and a temporary dummy output file is being
rendered. Later we will either ignore this doctype altogether or find
a better way of rendering it.
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
Ward Bell
Peter Bacon Darwin