Improve login text

Author: bbimber

mGAP/resources/views/login.html

@@ -66,6 +66,6 @@
     </div>
 </form>
 <div class="otherLoginMechanismsSection" hidden>
-    <div class="auth-header">Users from these institutions can use their existing logins (after registration):</div>
+    <div class="auth-header">Registered users from the following institutions can log in using their home institution's credentials below:</div>
     <div class="otherLoginMechanismsContent"></div>
 </div>