Nozzle Wipe Vertical Zig-Zag

- Add configuration support for zigzags in either the X or Y axis, for
wipe pads significantly longer in one dimension.
- Add configuration for default number of zig-zag triangles, vs. a
magic number in `Marlin_main.cpp`.
- Update description of auto nozzle wiping to match functionality

Marlin/example_configurations/RigidBot/Configuration.h

@@ -980,13 +980,13 @@
 //
 // Available list of patterns:
 //   P0: This is the default pattern, this process requires a sponge type
-//       material at a fixed bed location, the cleaning process is based on
-//       "strokes" i.e. back-and-forth movements between the starting and end
-//       points.
+//       material at a fixed bed location. S defines "strokes" i.e.
+//       back-and-forth movements between the starting and end points.
 //
 //   P1: This starts a zig-zag pattern between (X0, Y0) and (X1, Y1), "T"
 //       defines the number of zig-zag triangles to be done. "S" defines the
-//       number of strokes aka one back-and-forth movement. As an example
+//       number of strokes aka one back-and-forth movement. Zig-zags will
+//       be performed in whichever dimension is smallest. As an example,
 //       sending "G12 P1 S1 T3" will execute:
 //
 //          --
@@ -1007,8 +1007,11 @@
 //#define NOZZLE_CLEAN_FEATURE
 
 #if ENABLED(NOZZLE_CLEAN_FEATURE)
-  // Number of pattern repetitions
+  // Default number of pattern repetitions
   #define NOZZLE_CLEAN_STROKES  12
+  
+  // Default number of triangles
+  #define NOZZLE_CLEAN_TRIANGLES  3
 
   // Specify positions as { X, Y, Z }
   #define NOZZLE_CLEAN_START_POINT { 30, 30, (Z_MIN_POS + 1)}