[css-logical] editorial: 'text-align' section can be removed

[MatsPalmgren]

css-logical claims that it adds text-align: start | end, but those values are already included in css-text,
so I think this section can and should be removed.

[fantasai]

This spec was originally based over CSS2, so it was scoped to cover all features defined in CSS2. That's why it's listed here--although its normative definition is in nonetheless deferred to css-text-3.

(The extra stuff from css-ui-3 and css-backgrounds-3 is because those specs were too far ahead in the process and couldn't be modified, so we had to stick those features here also. But maybe we can pull those out into their Level 4 drafts.)