Search should be linked from top bar

[ajparsons]

Possibly covered by https://github.com/mysociety/caps/issues/416 - but could use the word Search at the top.

[zarino]

There are two things people can search for on CAPE:

• A council (by postcode or name)
• Text matches in council documents

Our /search endpoint is intended for searching for text inside council documents, but it does also attempt to handle things that look like postcodes:

Maybe that’s a good enough kludge to allow us to just put single search input in the nav, sending all searches to /search?

Could progressively enhance the input with a council name autocomplete (like the postcode search input on the homepage) to catch council name searches before the form is even submitted.