Doc - remove tangential task library info, fix a few typos
Doc - remove tangential task library info, fix a few typos

It seemed out of place to have an explanation of how to use an external library in a non-Giraffe context, and a single link to the library should be sufficient for reference, so removed the extra details. Also fixed a few typos throughout the document.
dustinmoris/AspNetCore.Lambda,dustinmoris/Giraffe,dustinmoris/Giraffe,dustinmoris/Giraffe