Add/edit README files for infra/recipes

Bug: skia:6473
Change-Id: I050df47a5a3f633263f0ca6258e83e96b78d7957
Reviewed-on: https://skia-review.googlesource.com/13123
Commit-Queue: Eric Boren <borenet@google.com>
Reviewed-by: Stephan Altmueller <stephana@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Ben Wagner <benjaminwagner@google.com>
3 files changed