Websites: Adding metadata to support the isPreview feature

[panchagnula]

---

This checklist is used to make sure that common guidelines for a pull request are followed.

General Guidelines

• Have you run ./scripts/ci/test_static.sh locally? (pip install pylint flake8 required)
• Have you run python scripts/ci/test_index.py -q locally?

For new extensions:

• My extension description/summary conforms to the Extension Summary Guidelines.

[azuresdkci]

If this PR is for a new extension or change to an existing extension, use the following to try out the changes in this PR:

docker run -it microsoft/azure-cli:latest
export EXT=<NAME>
pip install --upgrade --target ~/.azure/cliextensions/$EXT "git+https://github.com/panchagnula/azure-cli-extensions.git@sisirap-updatingNewToUp#subdirectory=src/$EXT&egg=$EXT"

[derekbekoe]

@panchagnula Change the description.
Also, you don't need the last comma after DEPENDENCIES

[derekbekoe]

Also, it's not azext_aem

[derekbekoe]

@panchagnula Please take a look at this PR otherwise I'll close soon. Thanks.

[panchagnula]

@derekbekoe i will get to this soon - sorry was out of office & now working on //BUILD work items.

[panchagnula]

@derekbekoe can you help me figure out the Travis CI build error?

[derekbekoe]

You need to add "azext.isPreview": true here also.