Docs: Fix some minor errors in tap dance example (#3530)

* Fix some minor errors in tap dance example

Fix for #3529
Fix minor errors in the code examples for __Example 4: 'Quad Function Tap-Dance'__ and relevant documentation. 
Clarified the need to include the header file in `keymap.c`.

* Use #pragma once in header guard

Fix for #3529
Implement change requested in #3530

docs/feature_tap_dance.md

@@ -196,22 +196,20 @@ SRC += your_name.c
 Pretty simple. It is a nice way to keep some rules common on all your keymaps.
 
 
-### In `/qmk_firmware/users/<your_name>/<you_name>.h`
+### In `/qmk_firmware/users/<your_name>/<your_name>.h`
 
 You will need a few things in this file:
 
 ```c
-#ifndef YOUR_NAME
+#pragma once
-#define YOUR_NAME
 
 #include "quantum.h"
 #include "process_keycode/process_tap_dance.h"
 
-
 typedef struct {
   bool is_press_action;
   int state;
-} xtap;
+} tap;
 
 enum {
   SINGLE_TAP = 1,
@@ -225,9 +223,9 @@ enum {
 
 //Tap dance enums
 enum {
-    CTL_X = 0,
+  X_CTL = 0,
   SOME_OTHER_DANCE
-}
+};
 
 int cur_dance (qk_tap_dance_state_t *state);
 
@@ -241,7 +239,7 @@ void x_reset (qk_tap_dance_state_t *state, void *user_data);
 And then in your user's `.c` file you implement the functions above:
 
 ```c
-#include "gordon.h"
+#include "<your_name>.h"
 #include "quantum.h"
 #include "action.h"
 #include "process_keycode/process_tap_dance.h"
@@ -335,4 +333,4 @@ qk_tap_dance_action_t tap_dance_actions[] = {
 };
 ```
 
-And then simply use TD(X_CTL) anywhere in your keymap.
+And then simply use `TD(X_CTL)` anywhere in your keymap after including `<your_name>.h`.