Tidy up docs

[SueSmith]

Doing any outstanding doc tidying here https://github.com/mozilla/badgekit-api/tree/doc-tidy/docs

[SueSmith]

Will update as per issues listed in #91

[SueSmith]

And include migration guidance as per #97

[SueSmith]

NB Have added links to the updated docs in the API repo wiki guides.

[cmcavoy]

Also need to add migration info to the README.md, it still refers to the schema.sql.

[SueSmith]

@cmcavoy - Will do, readme could probably use an update generally..

[SueSmith]

Migration info added to:

• readme https://github.com/mozilla/badgekit-api/blob/doc-tidy/README.md
• self-hosting guide https://github.com/mozilla/openbadges-badgekit/wiki/BadgeKit-Self-Hosting-Guide#set-up-badgekit-api
• wiki home https://github.com/mozilla/badgekit-api/wiki

[SueSmith]

Also todo: add instance delete webhook as in #111 (to docs and wiki pages)

[SueSmith]

p.s. just realised @christensenep has already added main revoke stuff to webhooks doc, so just needs added to other relevant bits..

[SueSmith]

Revoke info added to relevant wiki pages (haven't gone into much detail, mainly pointed to in-app docs).

[SueSmith]

Added pagination info to docs re. #113
Also added to retrieving badges guide: https://github.com/mozilla/badgekit-api/wiki/Retrieving-Badges#pagination

[threeqube]

👍

[SueSmith]

New routes added for milestones (adding/ removing a badge): https://github.com/mozilla/badgekit-api/blob/doc-tidy/docs/milestones.md

As per #88

[SueSmith]

I've changed the badges doc to reflect the auto-generated badge slugs: https://github.com/mozilla/badgekit-api/blob/doc-tidy/docs/badges.md

Removed slug from create and update endpoints - also removed the duplicate entry errors from those endpoints. Hope that sounds right!