chore: README.md

README.md

@@ -139,4 +139,5 @@ spellbook my-spell target=127.0.0.1
 - Namespaces
 
 ## Known issues
-- `KEY=VAL my-cmd` inline environment variable syntax is currently not supported (will fail with `executable file not found in $PATH`)
+- `KEY=VAL my-cmd` inline environment variable syntax is currently not supported (will fail with `executable file not found in $PATH`)
+- Shell operators (such as `|`, `>>`, etc.) are not yet supported