README.md in rcee_system-0.2.0 vs README.md in rcee_system-0.3.0

- old
+ new
@@ -76,9 +76,20 @@
 
 ``` text
 	libyaml-0.so.2 => /usr/lib/x86_64-linux-gnu/libyaml-0.so.2 (0x00007f345a3dc000)
 ```
 
+
+## Testing
+
+See [.github/workflows/system.yml](../.github/workflows/system.yml)
+
+Key things to note:
+
+- matrix across all supported Rubies and platforms
+- use the github action `MSP-Greg/setup-ruby-pkgs@v1` to install system libraries on each platform
+
+
 ## What Can Go Wrong
 
 In addition to what's enumerated in `isolated`'s README ...
 
 If `MakeMakefile` methods fail to find the third-party library (or fail to compile and link against it), then the user will see an error message, and have to go figure out how to install `libyaml` on their system.