update docs for regrass

docs/plugins/regrass.rst

@@ -1,3 +1,14 @@
 regrass
 =======
-Regrows all the grass. Not much to it ;)
+Tags:
+:dfhack-keybind:`regrass`
+
+Regrows all the grass. Use this command if your grazers have eaten everything
+down to the dirt.
+
+Usage::
+
+    regrass [max]
+
+Specify the 'max' option to pack more grass onto a tile than what the game
+normally allows to give your grazers extra chewing time.

plugins/regrass.cpp

@@ -29,8 +29,10 @@ command_result df_regrass (color_ostream &out, vector <string> & parameters);
 
 DFhackCExport command_result plugin_init (color_ostream &out, std::vector<PluginCommand> &commands)
 {
-    commands.push_back(PluginCommand("regrass", "Regrows surface grass.", df_regrass, false,
+    commands.push_back(PluginCommand(
-        "Specify parameter 'max' to set all grass types to full density, otherwise only one type of grass will be restored per tile.\n"));
+        "regrass",
+        "Regrows surface grass.",
+        df_regrass));
     return CR_OK;
 }