Add etesync documentation url

app/src/main/java/org/tasks/caldav/BaseCaldavAccountSettingsActivity.java

@@ -284,6 +284,8 @@ public abstract class BaseCaldavAccountSettingsActivity extends ThemedInjectingA
 
   protected abstract void updateAccount();
 
+  protected abstract String getHelpUrl();
+
   protected void requestFailed(Throwable t) {
     hideProgressIndicator();
 
@@ -389,7 +391,7 @@ public abstract class BaseCaldavAccountSettingsActivity extends ThemedInjectingA
   public boolean onMenuItemClick(MenuItem item) {
     switch (item.getItemId()) {
       case R.id.help:
-        startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("http://tasks.org/caldav")));
+        startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(getHelpUrl())));
         break;
       case R.id.remove:
         removeAccountPrompt();

app/src/main/java/org/tasks/caldav/CaldavAccountSettingsActivity.java

@@ -82,6 +82,11 @@ public class CaldavAccountSettingsActivity extends BaseCaldavAccountSettingsActi
     updateAccount(caldavAccount.getUrl());
   }
 
+  @Override
+  protected String getHelpUrl() {
+    return "http://tasks.org/caldav";
+  }
+
   @Override
   public void inject(ActivityComponent component) {
     component.inject(this);

app/src/main/java/org/tasks/etesync/EteSyncAccountSettingsActivity.java

@@ -109,6 +109,11 @@ public class EteSyncAccountSettingsActivity extends BaseCaldavAccountSettingsAct
     updateAccount(null);
   }
 
+  @Override
+  protected String getHelpUrl() {
+    return "http://tasks.org/etesync";
+  }
+
   @Override
   public void inject(ActivityComponent component) {
     component.inject(this);