[em] Extension name and description should be selectable

[peterflynn]

It feels natural for big blocks of static text to be selectable. Copying extension names is useful too, e.g. for someone who wanted to IM their coworker the name of a useful extension.

[pthiess]

Reviewed @njx

[jasonsanjose]

FBNC @dangoor since @peterflynn and @njx are out. cc @WebsiteDeveloper

[dangoor]

Confirmed that the extension name (and other big blocks of text) are now selectable.