Update docs
Summary:
* Add links to original wiki pages which can be used for tracking original authors and history.
* Update a bunch of links to point to static docs instead of wiki.
* Turn "Updating the thrift compiler in www" into a section.
* Remove the Debugging Issues section for now since it doesn't have any content.
* Fix a few images that were accidentally corrupted when retrieving from the wiki with wget.
* Move the style guide from the specs to a separate section under Best Practices per earlier discussion. Don't mention constants in the style guide yet since we don't have an agreed upon naming convention. The rest seems fairly uncontroversial and consistent with what we do now.
* Remove mentioning of `Duration` and `Timestamp` because those are not implemented.
* Cross out the part about Admission control since the latter has been removed (see e.g.
D29172961).
* Fix a bunch of formatting issues.
* Import CodeFrameworks migration guide which was added recently.
Reviewed By: iahs
Differential Revision:
D41604158
fbshipit-source-id:
a74232d9712ba579a7795aea6239f08589fd03df