Update cipd.md with acl-edit example

NoTry: true
Change-Id: Ibe620664f28f16338e5860ebc24c7ca89941b095
Reviewed-on: https://chromium-review.googlesource.com/1060170Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: agrieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#558906}

docs/cipd.md

@@ -133,6 +133,7 @@ Once you have those, you can create your package like so:
 ```
 # Assuming that the third-party dependency in question is at version 1.2.3
 # and this is the first chromium revision of that version.
+$ cipd auth-login  # One-time auth.
 $ cipd create --pkg-def cipd.yaml -tag version:1.2.3-cr0
 ```
 
@@ -197,6 +198,12 @@ $ cipd acl-list chromium
 By default, [cria/project-chromium-cipd-owners][4] own all CIPD packages
 under `chromium/`. If you're adding a package, talk to one of them.
 
+To obtain write access to a new package, ask an owner to run:
+
+```
+$ cipd acl-edit chromium/third_party/sample_cipd_dep -owner user:email@address.com
+```
+
 ## Troubleshooting
 
  - **A file maintained by CIPD is missing, and gclient sync doesn't recreate it.**