Request to make the unsubscribe instructions in the emails a little more descriptive

[designsimply]

The ability to subscribe to a topic by email was recently added. See #1366.

Could we make the unsubscribe instructions in the emails a little more descriptive?

Current:

• "You're getting this mail because you subscribed to the topic, visit the topic and login to unsubscribe."

Suggested:

• "You're getting this mail because you subscribed to the topic. To unsubscribe, click the 'Unsubscribe from Topic' link in the sidebar on the topic page while you are logged in."

[hanni]

Further attempt to clarify the wording and tidy up the repeated use of "topic" without context. Thanks JJJ! Props to andrewspittle, designsimply and hewsutton for suggestions.

[johnjamesjacoby]

Putting in 1.1 milestone to get in before tagging RC1

[westi]

Improved version of hanni's patch minus the minor bugs

[johnjamesjacoby]

(In [2912]) Clarify subscription notification email text. Props designsimply, hanni, westi. Fixes #1472.