Add trooper documentation for CT bots and for iOS "the service is invalid"

site/dev/sheriffing/trooper.md

Index: site/dev/sheriffing/trooper.md
diff --git a/site/dev/sheriffing/trooper.md b/site/dev/sheriffing/trooper.md
index 08d9388dcbe72c97ebdbb00518675142895690f7..aff146542a2b5be627707c22ed647550e060367d 100644
--- a/site/dev/sheriffing/trooper.md
+++ b/site/dev/sheriffing/trooper.md
@@ -60,8 +60,9 @@ Tips for troopers
   failing.)
 
 - Where machines are located:
-  - Machine name like "skia-vm-NNN" -> GCE
+  - Machine name like "skia-vm-NNN", "ct-vm-NNN" -> GCE
   - Machine name ends with "a3", "a4", "m3" -> Chrome Golo
+  - Machine name ends with "m5" -> CT bare-metal bots in Chrome Golo
   - Machine name starts with "skiabot-" -> Chapel Hill lab
   - Machine name starts with "win8" -> Chapel Hill lab (Windows machine
     names can't be very long, so the "skiabot-shuttle-" prefix is dropped.)
@@ -94,6 +95,8 @@ Tips for troopers
     - Machine name ends with "a3" or "a4" -> ssh command looks like `ssh
       build3-a3.chrome`
     - Machine name ends with "m3" -> ssh command looks like `ssh build5-m3.golo`
+    - Machine name ends with "m5" -> ssh command looks like `ssh build1-m5.golo`.
+      [Example bug](https://bugs.chromium.org/p/chromium/issues/detail?id=638193) to file to Infra Labs.
     - For MacOS and Windows bots, you will be prompted for a password, which is
       stored on [Valentine](https://valentine.corp.google.com/) as "Chrome Golo,
       Perf, GPU bots - chrome-bot".
@@ -112,3 +115,5 @@ Tips for troopers
   disconnected, you may need to start it manually. On Mac and Linux, check using
   `ps aux | grep python` that neither buildbot nor gclient are running, then run
   `~/skiabot-slave-start-on-boot.sh`.
+
+- Sometimes iOS builds fail with 'The service is invalid' ([example](https://luci-milo.appspot.com/swarming/task/30cb43e1e391d410/steps/nanobench/0/stdout)). Try rebooting the iOS host to fix this.

[stephana, 2016/08/22 15:22:01]

Question: Will the milo link vanish and make this example not useful anymore? 
IMO you could include the error message itself which would be shorter. 

[rmistry, 2016/08/22 15:58:42]

No idea, I guess that could happen. I went ahead and removed the example since
'The service is invalid' is already mentioned here.