Fix main github repo links in docs

This updates all references from github.com/runtimeco to
github.com/JuulLabs-OSS in docs and yml files.

Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/testplan/mynewt/project.yml b/testplan/mynewt/project.yml
index 1989014..a268f4f 100644
--- a/testplan/mynewt/project.yml
+++ b/testplan/mynewt/project.yml
@@ -32,5 +32,5 @@
 repository.mcuboot:
     type: github
     vers: 0-dev
-    user: runtimeco
+    user: JuulLabs-OSS
     repo: mcuboot