docs(ngIf): remove invalid comment from CSS

We cannot use valid /* ... */ CSS comments in examples because they break the parsing
of the ngdoc comments.  We can't use inline // comments because these are not valid in
CSS.

We could use the //!annotate extension to the ngdoc parser but this does not seem to be
working.  It is best to simply remove this line.

Closes #5234
docs(css): improve definition table style

Text in definition tables are now aligned to the top of the cell. These are used in
the API index page and makes it cleared what headings match what content.

Closes #5286
docs(ng): fix typo and line lengths

Closes #5288
docs(tutorial/step-0): fix twitter bootstrap link

The url of twitter bootstrap was outdated.

Closes #5290
docs($resource): add example for a custom PUT request

Closes #5302
docs(): fix jshint issues
docs(tutorial/step-11): change "last" to "next"

Since step 12 was added, step 11 is not the last. So this is not the last improvement.

Closes #5306
fix(select): invalidate when 'multiple`, `required` and model is `[]`

When `multiple` attribute is set on a `<select>` control and the model value is an empty array,
we should invalidate the control.  Previously, this directive was using incorrect logic for
determining if the model was empty.

Closes #5337