Added Firefox Android instructions for setting whoogle as primary search engine

README.md

@@ -146,6 +146,14 @@ Update browser settings:
     - In the mobile app Settings page, tap "Search" within the "General" section. There should be an option titled "Add Search Engine" to select. It should prompt you to enter a title and search query url - use the following elements to fill out the form:
       - Title: "Whoogle"
       - URL: "https://\<your whoogle url\>/search?q=%s"
+  - Firefox (Android)
+    - Navigate to your app's url
+    - Long-press on the search text field
+    - Click the "Add Search Engine" menu item
+      - Select a name and click ok
+    - Click the 3 dot menu in the top right
+    - Navigate to the settings menu and select the "search" sub-menu
+    - Select Whoogle and press "Set as default"
   - Others (TODO)
 
 ### Customizing and Configuration