"system name" --> "operating system", rmv examples

I think the connection with -s is still reasonably discernible, and the term OS is less ambiguous than just "system", so it doesn't need examples.

pages/common/uname.md

@@ -6,7 +6,7 @@
 
 `uname -mp`
 
-- Print software-related information: system name (Linux, Darwin...), release number, and version
+- Print software-related information: operating system, release number, and version
 
 `uname -srv`