Allow BIOS.protocol.{maxBytesPerSecond, maxBytesInTransit} to be set from BIOSConfig.lua

This modifies Protocol.lua so that values set in BIOSConfig.lua for maxBytesPerSecond and maxBytesInTransit are not overwritten by the defaults.

Refs #17.
Update userguide.adoc
Update userguide.adoc

Text changes made but need basic proof reading for typo's.  Picture to be added next time.
userguide.adoc: small corrections
User Guide: add A-10C-specific notes

Refs #19
Refs #14
Merge pull request #22 from jboecker/userguide-updates

Userguide updates: Rewrites, clarifications, A-10C notes
update README

The old README document had a broken link and most of the information
it provided has now been moved to the User Guide and Developer Guide
anyway.

This new one gives a general overview of what you can actually do
with DCS-BIOS.

Once we release the first version, we may want to update the documentation
links to point to the latest stable version.
README update: add link to "new issue" page
Update userguide.adoc