docs(dialog): add doc for align attribute (#15500)
docs(dialog): add doc for align attribute (#15500)

Adds a sentence to the docs about the `align` attribute of the dialog content. We can't document it through doc strings, because it isn't defined in TS.

Fixes #15482.
DevVersion/material2,andrewseguin/material2,mmalerba/material2,angular/components,Jefiozie/material2,mmalerba/material2,angular/components,DevVersion/material2,DevVersion/material2,crisbeto/material2,mmalerba/material2,andrewseguin/material2,DevVersion/material2,jelbourn/material2,andrewseguin/material2,Jefiozie/material2,Jefiozie/material2,angular/components,DevVersion/material2,josephperrott/material2,Jefiozie/material2,crisbeto/material2,josephperrott/material2,jelbourn/material2,josephperrott/material2,jelbourn/material2,angular/components,crisbeto/material2,jelbourn/material2,mmalerba/material2,crisbeto/material2,josephperrott/material2,andrewseguin/material2,mmalerba/material2,andrewseguin/material2,Jefiozie/material2,josephperrott/material2,jelbourn/material2