readme: fixup Firefox instructions

Author: FiloSottile

README.md

@@ -132,8 +132,8 @@ You can also resolve links locally using a snapshot file:
 
 If you're using Firefox, you might want to configure two options to make it easy to load links:
 
-    * to prevent `go/` page loads from the address bar being treated as searches,
-      navigate to `about:config` and add a boolean setting `browser.fixup.domainwhitelist.go`
-      with a value of _true_
-    
-    * if you use HTTPS-Only Mode, [add an exception](https://support.mozilla.org/en-US/kb/https-only-prefs#w_add-exceptions-for-http-websites-when-youre-in-https-only-mode)
+  * to prevent `go/` page loads from the address bar being treated as searches,
+    navigate to `about:config` and add a boolean setting `browser.fixup.domainwhitelist.go`
+    with a value of _true_
+
+  * if you use HTTPS-Only Mode, [add an exception](https://support.mozilla.org/en-US/kb/https-only-prefs#w_add-exceptions-for-http-websites-when-youre-in-https-only-mode)