Add split keyboard example for Bootmagic Lite (#16349)

* Add split keyboard example for bootmagic lite

* Add handedness link

* Edit sentence structure

* Apply suggested language correction

docs/feature_bootmagic.md

@@ -23,14 +23,35 @@ And to trigger the bootloader, you hold this key down when plugging the keyboard
 
 ## Split Keyboards
 
-When handedness is predetermined via an option like `SPLIT_HAND_PIN`, you might need to configure a different key between halves. To do so, add these entries to your `config.h` file:
+When [handedness](feature_split_keyboard.md#setting-handedness) is predetermined via options like `SPLIT_HAND_PIN` or `EE_HANDS`, you might need to configure a different key between halves. To identify the correct key for the right half, examine the split key matrix defined in the `<keyboard>.h` file, e.g.:
+
+```c
+#define LAYOUT_split_3x5_2( \
+        L01, L02, L03, L04, L05,   R01, R02, R03, R04, R05, \
+        L06, L07, L08, L09, L10,   R06, R07, R08, R09, R10, \
+        L11, L12, L13, L14, L15,   R11, R12, R13, R14, R15, \
+                       L16, L17,   R16, R17                 \
+    ) \
+    { \
+        { L01, L02, L03, L04, L05 }, \
+        { L06, L07, L08, L09, L10 }, \
+        { L11, L12, L13, L14, L15 }, \
+        { L16, L17, KC_NO, KC_NO, KC_NO }, \
+        { R01, R02, R03, R04, R05 }, \
+        { R06, R07, R08, R09, R10 }, \
+        { R11, R12, R13, R14, R15 }, \
+        { R16, R17, KC_NO, KC_NO, KC_NO }  \
+    }
+```
+
+If you pick the top right key for the right half, it is `R05` on the top layout. Within the key matrix below, `R05` is located on row 4 columnn 4. To use that key as the right half's Bootmagic Lite trigger, add these entries to your `config.h` file:
 
 ```c
 #define BOOTMAGIC_LITE_ROW_RIGHT 4
-#define BOOTMAGIC_LITE_COLUMN_RIGHT 1
+#define BOOTMAGIC_LITE_COLUMN_RIGHT 4
 ```
 
-By default, these values are not set.
+?> These values are not set by default.
 
 ## Advanced Bootmagic Lite