kdesrc-build: update page (#12290)

pages/linux/kdesrc-build.md

@@ -30,3 +30,7 @@
 - Build all configured components:
 
 `kdesrc-build`
+
+- Use system libraries in place of a component if it fails to build:
+
+`kdesrc-build --no-stop-on-failure {{component_name}}`