Register interest in knowing about local teams that may be created in future to search results page

[sequencefree]

Next steps

• [ ] @zarino to consider implementation options.

Background User story: As a householder I want the option to know about teams near me that are created in future so that I can consider joining one (especially if there are no teams near me now and I don't want to set one up).

Siôn assumes email alerts that users can turn on/off in profile would be good but if we don't build that for Alpha could be another heading/para/button combo on this page (suggested copy below).

Adapted legacy copy below:

Subscribe to new team alerts Not ready to start your own team? We can let you know when new teams are created near you, or when more people in your neighbourhood sign up.

Related: #19 & #26

[zarino]

There is now a (non-functional) button for this, on the search results page: