docs: fix missing space in mdc-dialog readme (#20542)
docs: fix missing space in mdc-dialog readme (#20542)

Fixes a missing space in the MDC dialog readme.
josephperrott/material2,josephperrott/material2,crisbeto/material2,mmalerba/material2,angular/components,DevVersion/material2,andrewseguin/material2,mmalerba/material2,angular/components,angular/components,mmalerba/material2,mmalerba/material2,andrewseguin/material2,crisbeto/material2,mmalerba/material2,crisbeto/material2,DevVersion/material2,andrewseguin/material2,andrewseguin/material2,crisbeto/material2,josephperrott/material2,DevVersion/material2,josephperrott/material2,josephperrott/material2,angular/components,DevVersion/material2,DevVersion/material2,andrewseguin/material2