Create commands.md (actions#105)

* Create commands.md

* Feedback

* Update action-debugging.md

docs/action-debugging.md

@@ -18,7 +18,7 @@ All actions ran while this secret is enabled contain additional diagnostic log f
 ## Step Debug Logs
 Step debug logs increase the verbosity of a job's logs during and after a job's execution to assist with troubleshooting. 
 
-Additional log events with the prefix `##[debug]` will now also appear in the job's logs.
+Additional log events with the prefix `::debug::` will now also appear in the job's logs.
 
 ### How to Access Step Debug Logs
 This flag can be enabled by [setting the secret](https://help.github.com/en/articles/virtual-environments-for-github-actions#creating-and-using-secrets-encrypted-variables) `ACTIONS_STEP_DEBUG` to `true`.

docs/commands.md

@@ -0,0 +1,70 @@
+# :: Commands
+
+The [core toolkit package](https://github.com/actions/toolkit/tree/master/packages/core) offers a number of convenience functions for
+setting results, logging, registering secrets and exporting variables across actions. Sometimes, however, its useful to be able to do
+these things in a script or other tool.
+
+To allow this, we provide a special `::` syntax which, if logged to `stdout`, will allow the runner to perform special behavior on
+your commands. The following commands are all supported:
+
+### Set an environment variable
+
+To set an environment variable, use `::set-env`:
+
+```sh
+echo ::set-env name=FOO::BAR
+```
+
+Running `$FOO` in a future step will now return `BAR`
+
+### PATH Manipulation
+
+To prepend a string to PATH, use `::addPath`:
+
+```sh
+echo ::add-path::BAR
+```
+
+Running `$PATH` in a future step will now return `BAR:{Previous Path}`;
+
+### Set outputs
+
+To set an output for the step, use `::set-output`:
+
+```sh
+echo ::set-output name=FOO::BAR
+```
+
+Running `steps.[step-id].outputs.FOO` in your Yaml will now give you `BAR`
+
+```yaml
+steps:
+  - name: Set the value
+    id: step_one
+    run: echo ::set-output name=FOO::BAR
+  - name: Use it
+    run: echo ${{ steps.step_one.outputs.FOO }}
+```
+
+### Masking Values in Logs
+
+To mask a value in the logs, use `::add-mask`:
+
+```sh
+echo ::add-mask::BAR
+```
+
+Now, future logs containing BAR will be masked. E.g. running `echo "Hello FOO BAR World"` will now print `Hello FOO **** World`.
+
+CAUTION: Do **not** mask short values if you can avoid it, it could render your output unreadable (and future steps' output as well).
+For example, if you mask the letter `l`, running `echo "Hello FOO BAR World"` will now print `He*********o FOO BAR Wor****d`
+
+### Log Level
+
+Finally, there are several commands to emit different levels of log output:
+
+| log level | example usage |
+|---|---|
+| [debug](https://github.com/actions/toolkit/blob/master/docs/action-debugging.md)  | `echo ::debug::My debug message` |
+| warning | `echo ::warning::My warning message` |
+| error | `echo ::error::My error message` |