Documentation for collections

[YarinHeffes]

We should have a document with a table describing the collections provided in the standard library. This table should include the functionality provided for each collection, along with time complexity for basic operations such as lookup. It can also contain a brief description of the implementation of the collection and perhaps even an example use case for each collection to illustrate, for example, how one should choose between HashTable and Map. This table is important for new Coalton users to get started right away, but it will also highlight missing features of certain collections, serving as a good place for developers to reference to decide how to make the collections more uniform, what features to add, and potentially what collections to add.