Documentation improvements

- Restructure the project README, moving the list of guides into a
README in the `Guides` directory
- Curate the `keyed(by:)` and `grouped(by:)` methods

Update changelog for 1.1.0 release (#206)

Rename `WindowsCollection` to `WindowsOfCountCollection`

Update the changelog/README for the 0.2.1 release (#145)

Update changelog for 0.2.0 release (#144)

Fix associated type inference error in release build (#130)

Update changelog for 0.1.0 release (#128)

Update changelog for 0.0.4 release (#120)

Update changelog for 0.0.3 release (#86)

Update changelog for 0.0.2 release