* Move the designated place for pkg_tar to be //pkg:tar.bzl.
This does not move pkg_tar from pkg.bzl to pkg/private/tar.bzl yet.
I am waiting on that for other PRs to pkg.bzl to be merged. This PR
moves the examples and tests to the desired style now rather than later.
* update docs snapshot because //pkg/private/tar:build_tar moved
* Reorganize the source tree
- WORKSPACE moves up one level
- this makes //:pkg.bzl effectively //pkg:pkg.bzl
- put forwarders in place at top level to not break anyone
- tests moves up one level
- toolchains moves up one level
- examples/**/BUILD do not change to the new rule locations
- this is explicitly to provide some proof that the forwarders work
- new examples should use the proper paths to .bzl files
- near the 1.x release we can clean the current ones up
Fixes: #111