Inform new users what GENERIC and NOTES are. These are useful for people
perusing the tree without a great deal of specific fbsd knowledge.
See discussion of r334073 for further motivation.
Requested by: jhb
Rework the README to make it a little easier for new users. This is the
first file many will see when persuing the FreeBSD source code so
- remove some of the text describes how to build. This is better covered
in the linked documentation.
- add a small blurb for what FreeBSD is. Some users might find this
document through features such as github search so they may not even
know what the project is
generally, gear this file for the new, accidental, or casual user rather
than towards someone seeking fuller documentation.
