add "other libraries" section to readme

reword readme

README.md

@@ -17,13 +17,14 @@ Rust's BTree implementation uses a branching factor of 11. This means even if
 the allocator were in a state where it had ~100,000 separate free-regions, a
 worst-case lookup will traverse only 5 tree nodes.
 
+
 ### `#![no_std]`
 
-This crate is `no_std`, but requires `alloc` for the BTree implementation.
+This crate is `no_std`, but requires the `alloc` crate for the BTree
+implementation.
 
 
-Future Work
------------
+### Future Work
 
 Currently, the BTree implementation at the heart of `orderly-allocator` asks
 the global-allocator for memory for newly-created nodes every now and then. It
@@ -32,16 +33,32 @@ a different BTree implementation which pulled new nodes from a predetermined
 & bounded set.
 
 
+### Other Libraries
+
+Other libraries in the ecosystem that might serve a similar purpose:
+
+- [offset-allocator], A Rust port of Sebastian Aaltonen's
+  [C++ package][sebbbi/OffsetAllocator] of the same name.
+- [lru-slab], A datastructure for managing elements with a uniform size in
+  constant time.
+
+[offset-allocator]: https://github.com/pcwalton/offset-allocator
+[sebbbi/OffsetAllocator]: https://github.com/sebbbi/OffsetAllocator
+[lru-slab]: https://github.com/Ralith/lru-slab
+
+
 License
 -------
 
-This crate is licensed under any of the
-[Apache license, Version 2.0](./LICENSE-APACHE),
-or the
-[MIT license](./LICENSE-MIT),
-or the
-[Zlib license](./LICENSE-ZLIB)
-at your option.
+This crate is licensed under any of the [Apache license 2.0], or the
+[MIT license], or the [Zlib license] at your option.
+
+[Apache license 2.0]: ./LICENSE-APACHE
+[MIT license]: ./LICENSE-MIT
+[Zlib license]: ./LICENSE-ZLIB
+
+### Contribution
 
 Unless explicitly stated otherwise, any contributions you intentionally submit
-for inclusion in this work shall be licensed accordingly.
+for inclusion in this work shall be licensed as above, without any additional
+terms or conditions.