Follow-up to #14788 that allowed `ng doc --version 6`.
This commit enhances the doc command to use the current Angular version of the project by default, if no version is provided explicitely.
Fixes#12365
As the JSON Schema validation is minimum in the CLI, we have to also validate in code.
This PR:
- updates the JSON Schema to use `number` and `enum` instead of `integer` and `const` that are not supported.
- adds validation in the doc command implementation
- adds error reporting if the version is not valid
- fixes a typo in an error message in the parser
With this commit, we can now specify a `version`
for the `ng doc` command
ng doc --version 6
ng doc -v 6
and this will open `v6.angular.io` instead of `angular.io`.
The default domain is still used
if no version is specified.
Refs #12365
