Major re-org and update of docs
Adding confirming message delivery section
Adding transition guide and changelog
Updating TypingIndicators documentation on Android
Small docs changes
Merging abirs
Update typing-indicator.md

Changed LayerKit to Layer SDK; corrected 10-second timeout to "a few seconds" (since it's 3 on the sender and 5 on the receiver, which is aligned with iOS).
Updating Metadata documentation on Android
Merge branch 'coleman-reorg' of github.com:layerhq/documentation into coleman-reorg
Updating typo on Metadata documentation on Android
Updating 2nd typo on Metadata documentation
Update metadata.md

Corrected Android classes; Corrected for 0.8.9 methods; Switched from JSON to standard Map.
Updating docs