One entry uses second-hand instead of secondhand. fix that.
Add a file listing all the fields currently in bookshops.txt.

Ordered in a useful way and with some comments.
Add a note that fields are documented in fields.txt
Add photo for Chorleywood Bookshop.
Merge pull request #5 from rjw1/second-hand

One entry uses second-hand instead of secondhand. Fix that.
Merge pull request #6 from rjw1/fields

Document the fields.
Fix copy-paste error for Books Ink.
Merge branch 'master' of github.com:KakeLP/london-bookshop-map
Correct and expand fields.txt
Disambiguate some display names, add photo for Loughton Book Shop.