Modifications (grammar and references) to the docs

Corrected a couple of (what I think are) grammatical errors.

Added a cross reference to the known toolchains in the WRF example.

Changed the appending to the $MODULEPATH to use `module use` as
Lmod compains if you change it's path on it.
Changes in line with Kenneth's comments.

Changed the module path to refer to the module search path.
Updated the reference to the toolchain used in the WRF example.
Changed the explination in the command line usage section of the goolf
toolchain.
Merge pull request #46 from tbrown-curc/develop

Modifications (grammar and references) to the docs