Add payment flow content per bug 861968

I nested some <ul>s and added some <ol> numbered steps.
Make free with in_app separate to price tier 0 (bug 887994)
Merge pull request #863 from muffinresearch/split-free-inapp-and-tier-0-887994

Make free with in_app separate to price tier 0 (bug 887994)
only allow searching and purchasing in specified regions (bug 889056)
Save account list info for free with in-app (bug 889454)
add in more countries to dev and stage
Merge pull request #864 from muffinresearch/save-payment-info-free-inapp-889454

Save account list info for free with in-app (bug 889454)
A little less mockery that doesn't leak
Merge pull request #861 from markgif/patch-2

Add payment flow content per bug 861968
whitespace fix to trigger fireplace
updated payments doc; bug 861968
fixed wording
Don't make a premium bango product for free in-app (bug 889529)
reorder some importants (trigger fireplace)
Merge pull request #866 from muffinresearch/fix-exception-for-free-inapp-889529

Don't make a premium bango product for free in-app (bug 889529)
use slug instead of id for cats in app install for linux (bug 876293)
concrete is just a mirror. irc is canonical
reject too-large packaged app uploads early with 413. (bug 861516)
some tests, to clear up doubts
bumpsies