Add a copy of docs/writing-tests from C TAP Harness as HOWTO and add
a README with some additional explanations more specific to OpenAFS.
Change-Id: Ic5b04805db6b00bcb82862ad8d2ebe466f2c266b
Reviewed-on: http://gerrit.openafs.org/2109
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Russ Allbery <rra@stanford.edu>
Tested-by: Russ Allbery <rra@stanford.edu>
