Add infor about delayed flights to the start page.

Fixes https://github.com/Khopa/dcs_liberation/issues/398

resources/ui/templates/mission_start_EN.j2

@@ -0,0 +1,58 @@
+<b>You are clear for takeoff</b>
+
+<p>
+  Some player flights may be delayed to start. For such flights, it will not be
+  possible to enter the cockpit for a delayed flight until its mission start
+  time, shown in the flight information window.
+</p>
+
+<p>
+  To reduce delays, schedule packages with player flights with an earlier TOT.
+  Note that if some flights within the package will take a long time to reach the
+  target, a player flight may still be delayed.
+</p>
+
+<p>
+  To avoid delays entirely, use the "Never delay player flights" option in the
+  mission generation settings. Note that this will <strong>not</strong> adjust
+  the timing of your mission; this option only allows you to wait in the
+  cockpit.
+</p>
+
+<p>
+  For more information, see the mission planning documentation on
+  <a href="https://github.com/Khopa/dcs_liberation/wiki/Mission-planning">
+    the wiki</a>.
+</p>
+
+<h2>For Singleplayer:</h2>
+
+<p>
+  In DCS, open the Mission Editor and load the file: <i>liberation_nextturn</i>.
+</p>
+
+<p>
+  Once the mission is loaded in the ME, use the "FLY" option in the "Flight"
+  menu to launch.
+</p>
+
+<h2>For Multiplayer:</h2>
+
+<p>
+  In DCS, open the Mission Editor, and load the file: <i>liberation_nextturn</i>
+</p>
+
+<p>Select File/Save, exit the mission editor, and then select Multiplayer.</p>
+
+<p>Then host a server with the mission, and tell your friends to join!</p>
+
+<i>(The step in the mission editor is important, and fix a game breaking bug.)</i>
+
+<h2>Finishing</h2>
+
+<p>Once you have played the mission, click on the \"Accept Results\" button.</p>
+
+<p>
+  If DCS Liberation does not detect mission end, use the manually submit button,
+  and choose the state.json file.
+</p>