add description

Author: roma-jam

.github/workflows/build_and_run_esp_usb_test_apps.yml

@@ -1,4 +1,8 @@
-name: ESP-USB Test Apps
+name: ESP-USB Test Apps [master]
+description: |
+  This workflow builds and runs ESP-USB test applications for pull requests.
+  It checks out the latest code from ESP-USB master, builds test apps using Espressif's IDF,
+  uploads artifacts, and runs tests on self-hosted runners for supported targets.
 
 on:
   pull_request: