BUG: Remove unescaped quotes in Markers description

because they broke the plugin and not needed anyway.
Line Profile does not have quotes around the l key mention.
This is a bug fix for #2709 .

jdaviz/configs/default/plugins/markers/markers.vue

@@ -1,6 +1,6 @@
 <template>
   <j-tray-plugin
-    :description="docs_description || 'Create and export markers.  Press "m" with the cursor over a viewer to log the mouseover information.  To change the selected layer, click the layer cycler in the mouseover information section of the app-level toolbar.'"
+    :description="docs_description || 'Create and export markers.  Press m with the cursor over a viewer to log the mouseover information.  To change the selected layer, click the layer cycler in the mouseover information section of the app-level toolbar.'"
     :link="docs_link || 'https://jdaviz.readthedocs.io/en/'+vdocs+'/'+config+'/plugins.html#markers'"
     :uses_active_status="uses_active_status"
     @plugin-ping="plugin_ping($event)"