Add initial production manual for fiddle.

Also try linking from alerts directory to the right area of the production manual.

BUG=skia:

Review-Url: https://codereview.chromium.org/1926793003

alertserver/alerts.cfg

diff --git a/alertserver/alerts.cfg b/alertserver/alerts.cfg
index 46cd543..8526c1d 100644
--- a/alertserver/alerts.cfg
+++ b/alertserver/alerts.cfg
@@ -649,7 +649,7 @@
 #
 [[rule]]
 name = "fiddle is failing to build"
-message = "Fiddle has failed to build at the last 2 chrome DEPS rolls. Search logs for \"Failed to build LKGR:\" and \"Successfully built:\"."
+message = "Fiddle has failed to build at the last 2 chrome DEPS rolls. https://skia.googlesource.com/buildbot/+/master/fiddle/PROD.md#build_fail"
 database = "skmetrics"
 query = "SELECT mean(value) FROM \"counter\" WHERE app='fiddle' AND \"name\"='builds-failed' AND time > now() - 10m"
 category = "infra"
@@ -660,7 +660,7 @@
 
 [[rule]]
 name = "fiddle is failing to sync"
-message = "Fiddle has failed to sync to HEAD at least 2 times in a row. Search logs for \"Failed to update skia repo\"."
+message = "Fiddle has failed to sync to HEAD at least 2 times in a row. https://skia.googlesource.com/buildbot/+/master/fiddle/PROD.md#sync_fail"
 database = "skmetrics"
 query = "SELECT mean(value) FROM \"counter\" WHERE app='fiddle' AND \"name\"='repo-sync-failed' AND time > now() - 10m"
 category = "infra"

fiddle/PROD.md

diff --git a/fiddle/PROD.md b/fiddle/PROD.md
new file mode 100644
index 0000000..3b072b0
--- /dev/null
+++ b/fiddle/PROD.md
@@ -0,0 +1,65 @@
+Fiddle Production Manual
+========================
+
+First make sure you are familar with the design of fiddle by reading the
+[DESIGN](./DESIGN.md) doc.
+
+
+Forcing a build
+---------------
+
+You may need for force a build on the server, say if you accidentally wiped
+the mounted drive, or say fiddle is broken and you need to force it to build
+at HEAD and not wait for that commit to make it into a DEPS rolls.
+
+SSH into `skia-fiddle` and run:
+
+    fiddle_build --force --head --alsologtostderr \
+      --depot_tools=/mnt/pd0/depot_tools \
+      --fiddle_root=/mnt/pd0/fiddle
+
+After that finishes restart fiddle:
+
+    sudo systemctl restart fiddle.service
+
+Or restart Fiddle from the push dashboard.
+
+Debugging fiddle\_secwrap.cpp
+-----------------------------
+
+Highly unlikely to be needed, but if font handling changes, for example, then
+Skia applications may start trying to read new directories or make exciting
+new system calls.
+
+If that happens then uncomment the line:
+
+        TRACE_ALL,
+
+in `fiddle_secwrap.cpp`, then compile and run fiddle\_secwrap locally and then
+run it over the offending exe to determine which calls it is making and then
+add those to the whitelist.
+
+Alerts
+======
+
+Items below here should include target links from alerts.
+
+Fiddle is failing to build <a id=build_fail></a>
+------------------------------------------------
+
+This usually isn't a critical error since Fiddle will only start
+using a build of Skia if it was successfully built, but this should
+be addressed so Fiddle doesn't get too far removed from Skia HEAD.
+
+Search logs for "Failed to build LKGR:" and "Successfully built:".
+
+Fiddle is failing to sync<a id=sync_fail></a>
+------------------------------------------------
+
+This sync is for Fiddle updating a local copy of Skia that's used
+to look up git hashes. The repo is located at /mnt/pd0/fiddle/skia.
+
+Search logs for "Failed to update skia repo".
+
+One easy fix is to SSH into the machine and delete the directory and
+then restart Fiddle, which will rebuild the checkout.