Library has inadequate documentation in the docs directory

[JordanMartinez]

Is your change request related to a problem? Please describe.
As described in the documentation section of the Library Guidelines, Contributors libraries are expected to have some documentation in the docs directory -- specifically, a changelog and at least a short tutorial that expands on the quick start in the README.

This library currently doesn't have an up to date changelog. While it does have the test/Examples.purs file as an example of how to write parsers, some things still do not have examples:

• what chain* functions do
• how to use buildExprParser and why one would use it over other combinators

Describe the solution you'd like
The changelog needs to be updated for at least the most recent release (we can then start curating it going forward) and at least a short tutorial needs to be added to the docs directory, or other documentation as described in this Divio article.

The argonaut-codecs docs directory has a good example of expanded documentation for a Contributor library. But it would even be useful to add something considerably smaller and shorter to this library.

Additional context
See the Governance repository for more information about requirements in the Contributors organization.