Include StickyLocking after Release

[vknabel]

StickyLocking has not been released yet. Once it has, we want to add it to the index.

Excerpt from #19:

StickyLocking: Complete, but not yet released. Plan to release it in beta shortly. I want to release it concurrently with StickyEncoding (https://github.com/stickytools/sticky-encoding) which still requires some documentation and readme updates.

#### Locking / Concurrency libraries
> _Tags: lock, locking, lock-manager, mutex, conditions, concurrency_
* [StickyLocking](https://github.com/stickytools/sticky-locking): A general purpose embedded hierarchical lock manager used to build highly concurrent applications of all types. Runs on ios, osx, and linux.