adding watcher instructions

README.md

@@ -112,7 +112,7 @@ In config.py, set **simulate=True**. Start the server and select a profile and c
 
 ### Watcher
 
-If you're busy and do not want to sit around watching the web interface for problems, there is a watcher.py script which you can run on any machine in your local network or even on the raspberry pi which will watch the kiln-controller process to make sure it is running a schedule, and staying within a pre-defined temperature range. When things go bad, it sends messages to a slack channel you define. I have alerts set on my android phone for that specific slack channel.
+If you're busy and do not want to sit around watching the web interface for problems, there is a watcher.py script which you can run on any machine in your local network or even on the raspberry pi which will watch the kiln-controller process to make sure it is running a schedule, and staying within a pre-defined temperature range. When things go bad, it sends messages to a slack channel you define. I have alerts set on my android phone for that specific slack channel. Here are detailed [instructions](https://github.com/jbruce12000/kiln-controller/blob/master/docs/watcher.md).
 
 ## License
 

docs/watcher.md

@@ -0,0 +1,26 @@
+### Watcher
+
+watcher.py is a watchdog for your kiln. It is a stand-alone python script that, every few seconds, verifies the kiln-controller.py process is running, and within a certain acceptable temperature range. By default it checks every 10s and after six failed checks, it sends a message to a slack channel. It can run on any network, but needs to be able to access the kiln and slack.
+
+Here are the configuration items to potentially set in that script:
+
+| Variable      | Purpose       | Required  | Default |
+| ------------- |-------------- | --------- | ------- |
+| kiln_url      | the url of the stats api endpoint | Yes | None |
+| slack_hook_url| the url of the slack channel to post failures | Yes | None |
+| bad_check_limit | send message after this many failures | No | 6 |
+| temp_error_limit | consider it a failure if temperature is this far off | No | 10 |
+| sleepfor | wait this many seconds between checks | No | 10 |
+
+### Slack
+
+[Slack](https://slack.com/) is a free messaging platform. It was is used to sendalerts when the watcher finds problems with your kiln.
+
+1. Sign up for a slack account
+2. Create a workspace, doesn't matter what you call it
+3. Create a channel in that workspace
+4. Set up an [incoming web hook](https://slack.com/help/articles/115005265063-Incoming-webhooks-for-Slack) in that channel.
+5. Grab the URL for that web hook and use it to set the slack_hook_url in the configuration
+
+If you configured slack, you can test it by starting the watcher without the kiln-controller running and after six failures to reach the kiln, it will send a notification to slack.
+