Group message notification email: change "Visit Topic" to "Visit Message"

[codinghorror (Jeff Atwood)]

@tobiaseigen

E.g. as relevant one of the following would be added ahead of the “To stop receiving…” text.

You received this because you were mentioned.
You received this because your @foo group was mentioned.
You received this because you are watching #foo category.
You received this because you are watching #foo tag.

That’s definitely a good idea…!