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/docs/readme-mynewt.md b/docs/readme-mynewt.md
index ee88ecb..c2e509d 100644
--- a/docs/readme-mynewt.md
+++ b/docs/readme-mynewt.md
@@ -14,7 +14,7 @@
     repository.mcuboot:
         type: github
         vers: 0-dev
-        user: runtimeco
+        user: JuulLabs-OSS
         repo: mcuboot
 ```