Add new landscape flag to enable drawing rocks covered by snow

docs/newgrf-newlandscape-nml.html

@@ -64,6 +64,12 @@
 				</table>
 			</td>
 		</tr>
+		<tr><td>enable_draw_snowy_rocks</td><td>0 or 1</td>
+			<td>
+				Enable drawing of rock tiles covered by snow, for this GRF.<br />
+				(This only takes effect from <font face="monospace">new_landscape</font> version 2).
+			</td>
+		</tr>
 	</table>
 
 	<h3 id="newlandscape_variables">New Landscape Variables</h3>

docs/newgrf-newlandscape.html

@@ -48,6 +48,7 @@
 	<table>
 		<tr><th>Mappable name</th><th>Size in bytes</th><th>Description</th></tr>
 		<tr><td><a href="#newlandscape_enable_recolour">newlandscape_enable_recolour</a></td><td>1</td><td>Enable recolour</td></tr>
+		<tr><td><a href="#newlandscape_enable_draw_snowy_rocks">newlandscape_enable_draw_snowy_rocks</a></td><td>1</td><td>Enable drawing rocky tiles covered by snow</td></tr>
 	</table>
 
 	<h4 id="newlandscape_enable_recolour">Enable recolouring for new landscape graphics (mappable property: newlandscape_enable_recolour)</h4>
@@ -59,6 +60,11 @@
 	</table></p>
 	<p>The property length is 1 byte. 0 is disabled (default). 1 is enabled.</p>
 
+	<h4 id="newlandscape_enable_draw_snowy_rocks">Enable drawing rocky tiles covered by snow (mappable property: newlandscape_enable_draw_snowy_rocks)</h4>
+	<p>When enabled, drawing of rocky tiles covered by snow is enabled for this GRF.</p>
+	<p>The property length is 1 byte. 0 is disabled (default). 1 is enabled.<br />
+	This requires <font face="monospace">new_landscape</font>, version 2.</p>
+
 	<h3 id="a2roadstops">Action 2 - New Landscape</h3>
 
 	<p>See the <a href="https://newgrf-specs.tt-wiki.net/wiki/Action2">Action 2 Specification</a> for background information.</p>