trivial docu fixes

Good day Nico!

(edited - i did not know that pull requests on Github will be modified automatically one I push new stuff to include all the new commits)

Until commit 5b8ab38 I've fixed half a dozen little typos, asciidoc syntax gotchas, slighlty improved wording (at least IMHO). Please have a look at the diff and in case it's OK, then please merge it in (pull..).

After that I've tried to improve the explication of how dependencies work in the manifest docu e5a1280 - [2]. Please have a look at it, if it's technically correct and also understandable for a human parser.

Third thing I did, was to have generated HTML man pages automatically crossreferenced. 454f955 - [3] includes also a little wording fix and an important fix to the crossreference generation.

Greets!
*t 

[1] https://github.com/tpo/cdist/commit/5b8ab385f2c3a6ebfed781e53766f3f39d3ae089
[2] https://github.com/tpo/cdist/commit/e5a12803ffd33ac3e08e2ffa56d9bdaeacdc3b7b
[3] https://github.com/tpo/cdist/commit/454f955d25221e34c9b13515487c56adc4010d59