Update chap08-military.rst

[jwoodward48gh]

Improved grammar and spelling, and removed a reference to drypumping (it no longer significantly trains any stats). Removed reference to unskilled dwarves hurting themselves or others when sparring - is no longer a thing.

[jwoodward48gh]

The war dog training is waaaaay out of date. Kennels haven't been needed for five years or so. Can somebody who's more knowledgeable about this stuff update the "War Puppies" section?

[PeridexisErrant]

Thanks so much for helping out -- before I merge this, it would be great if you could remove the trailing whitespace (see travis build details) and add yourself to the list of authors in misc/contributing.rst!