adds required test variables to .env-template with empty values

bigbluebutton-html5/tests/puppeteer/.env-template

+# meeting credentials
 BBB_SERVER_URL=""
-BBB_SHARED_SECRET=""
\ No newline at end of file
+BBB_SHARED_SECRET=""
+
+# collecting metrics
+BBB_COLLECT_METRICS=    # (true/false): true to collect metrics
+METRICS_FOLDER=     # full path of your audio.wav file
+
+# files paths for audio and webcams tests
+AUDIO_FILE=         # full path of your audio.wav file
+VIDEO_FILE=         # full path of your video.y4m file
+
+# webcams test
+LOOP_INTERVAL=      # time to loop in the webcams test in milliseconds
+CAMERA_SHARE_FAILED_WAIT_TIME=15000     # this is set by default in the BBB server
+
+# audio test
+IS_AUDIO_TEST=      # (true/false): true if the test will require enabling audio
\ No newline at end of file