Correct gwrite DocString

Author: tatarize

vpype_gcode/gwrite.py

@@ -45,6 +45,12 @@ def invert_axis(document: vp.Document, invert_x: bool, invert_y: bool):
 )
 @vp.global_processor
 def gwrite(document: vp.Document, output: typing.TextIO, profile: str):
+    """
+    Write gcode files for the vpype pipeline.
+
+    The output format can be customized by the user heavily to an extent that you can also output most known
+    non-gcode ascii text files.
+    """
     gwrite_config = vp.CONFIG_MANAGER.config["gwrite"]
 
     # If no profile was provided, try to use a default