gcode_macro: add description property (#4317)

Signed-off-by: Alex Zellner <alexander.zellner@googlemail.com>

docs/Command_Templates.md

@@ -27,6 +27,25 @@ Note how the `gcode:` config option always starts at the beginning of
 the line and subsequent lines in the G-Code macro never start at the
 beginning.
 
+### Add a description to your macro
+
+To help identify the functionality a short description can be added.
+Add `description:` with a short text to describe the functionality.
+Default is "G-Code macro" if not specified.
+For example:
+
+```
+[gcode_macro blink_led]
+description: Blink my_led one time
+gcode:
+  SET_PIN PIN=my_led VALUE=1
+  G4 P2000
+  SET_PIN PIN=my_led VALUE=0
+```
+
+This will be showing is you use the `HELP` command or use the autocomplete
+function.
+
 ### Save/Restore state for G-Code moves
 
 Unfortunately, the G-Code command language can be challenging to use.

docs/Config_Reference.md

@@ -1237,6 +1237,9 @@ G-Code macros (one may define any number of sections with a
 #   commands. Care should be taken when overriding commands as it can
 #   cause complex and unexpected results. The default is to not
 #   override an existing G-Code command.
+#description: G-Code macro
+#   This will add a short description used at the HELP command or while
+#   using the auto completion feature. Default "G-Code macro"
 ```
 
 ## [delayed_gcode]

klippy/extras/gcode_macro.py

@@ -124,6 +124,7 @@ class GCodeMacro:
         self.template = gcode_macro.load_template(config, 'gcode')
         self.gcode = printer.lookup_object('gcode')
         self.rename_existing = config.get("rename_existing", None)
+        self.cmd_desc = config.get("description", "G-Code macro")
         if self.rename_existing is not None:
             if (self.gcode.is_traditional_gcode(self.alias)
                 != self.gcode.is_traditional_gcode(self.rename_existing)):
@@ -177,7 +178,6 @@ class GCodeMacro:
         except ValueError as e:
             raise gcmd.error("Unable to parse '%s' as a literal" % (value,))
         self.variables[variable] = literal
-    cmd_desc = "G-Code macro"
     def cmd(self, gcmd):
         if self.in_script:
             raise gcmd.error("Macro %s called recursively" % (self.alias,))