update the command to be more meaningful

Author: dhilipkumars

extensions/selftest/commands/selftest.md

@@ -9,7 +9,7 @@ This command drives a self-test simulating the developer experience with the `$A
 ## Goal
 
 Validate the end-to-end lifecycle (discovery, installation, registration) for the extension: `$ARGUMENTS`.
-If `$ARGUMENTS` is empty, you must tell the user to provide an extension name, for example: `/speckit.selftest.run linear`.
+If `$ARGUMENTS` is empty, you must tell the user to provide an extension name, for example: `/speckit.selftest.extension linear`.
 
 ## Steps
 

extensions/selftest/extension.yml

@@ -11,6 +11,6 @@ requires:
   speckit_version: ">=0.1.0"
 provides:
   commands:
-    - name: speckit.selftest.run
+    - name: speckit.selftest.extension
       file: commands/selftest.md
       description: Validate the lifecycle of an extension from the catalog.