copy from testing/taskcluster/tasks/decision/try.yml
copy to .taskcluster.yml
--- a/testing/taskcluster/tasks/decision/try.yml
+++ b/.taskcluster.yml
@@ -1,36 +1,54 @@
 ---
+version: 0
 metadata:
-  name: 'Taskcluster decision task for {{project}}'
-  description: |
-    Try push for {{owner}}.
+  name: 'Taskcluster tasks for Gecko'
+  description: "The taskcluster task graph for Gecko trees"
   owner: mozilla-taskcluster-maintenance@mozilla.com
-  source: "{{{source}}}"
+  source: {{{source}}}
 
 scopes:
   # Note the below scopes are insecure however these get overriden on the server
   # side to whatever scopes are set by mozilla-taskcluster.
   - queue:*
   - docker-worker:*
   - scheduler:*
 
+# Available mustache parameters (see the mozilla-taskcluster source):
+#
+# - owner:          push user (email address)
+# - source:         URL of this YAML file
+# - url:            repository URL
+# - project:        alias for the destination repository (basename of
+#                   the repo url)
+# - level:          SCM level of the destination repository
+#                   (1 = try, 3 = core)
+# - revision:       (short) hg revision of the head of the push
+# - revision_hash:  (long) hg revision of the head of the push
+# - comment:        comment of the push
+# - pushlog_id:     id in the pushlog table of the repository
+#
+# and functions:
+# - as_slugid:      convert a label into a slugId
+# - from_now:       generate a timestamp at a fixed offset from now
+
 tasks:
   - taskId: '{{#as_slugid}}decision task{{/as_slugid}}'
     reruns: 3
     task:
       created: '{{now}}'
       deadline: '{{#from_now}}1 day{{/from_now}}'
       expires: '{{#from_now}}14 day{{/from_now}}'
       metadata:
         owner: mozilla-taskcluster-maintenance@mozilla.com
         source: {{{source}}}
-        name: "[tc] Initial decision task for try"
+        name: "Gecko Decision Task"
         description: |
-          Create the task-graph for a try push
+            The task that creates all of the other tasks in the task graph
 
       workerType: "gecko-decision"
       provisionerId: "aws-provisioner-v1"
 
       tags:
         createdForUser: {{owner}}
 
       scopes:
@@ -42,39 +60,34 @@ tasks:
 
       routes:
         - "index.gecko.v2.{{project}}.latest.firefox.decision"
         - "tc-treeherder.{{project}}.{{revision_hash}}"
         - "tc-treeherder-stage.{{project}}.{{revision_hash}}"
 
       payload:
         env:
+          # checkout-gecko uses these to check out the source; the inputs
+          # to `mach taskgraph decision` are all on the command line.
           GECKO_BASE_REPOSITORY: 'https://hg.mozilla.org/mozilla-central'
           GECKO_HEAD_REPOSITORY: '{{{url}}}'
           GECKO_HEAD_REF: '{{revision}}'
           GECKO_HEAD_REV: '{{revision}}'
 
         cache:
-          # The taskcluster-vcs tooling stores the large clone caches in this
-          # directory and will reuse them for new requests this saves about 20s~ and
-          # is the most generic cache possible.
           level-{{level}}-{{project}}-tc-vcs-public-sources: /home/worker/.tc-vcs/
           level-{{level}}-{{project}}-gecko-decision: /home/worker/workspace
 
         features:
           taskclusterProxy: true
 
         # Note: This task is built server side without the context or tooling that
         # exist in tree so we must hard code the version
         image: 'taskcluster/decision:0.1.0'
 
-        # Virtually no network or other potentially risky operations happen as part
-        # of the task timeout aside from the initial clone. We intentionally have
-        # set this to a lower value _all_ decision tasks should use a root
-        # repository which is cached.
         maxRunTime: 1800
 
         command:
           - /bin/bash
           - -cx
           - >
             mkdir -p /home/worker/artifacts &&
             checkout-gecko workspace &&