keyboardModifiers: split keys into smaller groups

Language/Functions/USB/Keyboard/keyboardModifiers.adoc contains a long
list of macros corresponding to keys. Make this list easier to parse by
organizing the keys into meaningful groups.

Author: edgar-bonet

Language/Functions/USB/Keyboard/keyboardModifiers.adoc

@@ -52,24 +52,44 @@ These are eight keys within the alphanumeric cluster of the keyboard that are me
 === Special keys
 These are all the keys that do not match a printable ASCII character and are not modifiers, including all keys outside the alphanumeric cluster.
 
+[float]
+==== Within the alphanumeric cluster
+
 |===
 |Key	|Hexadecimal value	|Decimal value
 
-|KEY_UP_ARROW   |0xDA |218
-|KEY_DOWN_ARROW |0xD9 |217
-|KEY_LEFT_ARROW |0xD8 |216
-|KEY_RIGHT_ARROW |0xD7 |215
-|KEY_BACKSPACE  |0xB2 |178
 |KEY_TAB        |0xB3 |179
+|KEY_CAPS_LOCK  |0xC1 |193
+|KEY_BACKSPACE  |0xB2 |178
 |KEY_RETURN     |0xB0 |176
-|KEY_ESC        |0xB1 |177
+|===
+
+[float]
+==== Navigation cluster
+
+|===
+|Key	|Hexadecimal value	|Decimal value
+
 |KEY_INSERT     |0xD1 |209
 |KEY_DELETE     |0xD4 |212
-|KEY_PAGE_UP    |0xD3 |211
-|KEY_PAGE_DOWN  |0xD6 |214
 |KEY_HOME       |0xD2 |210
 |KEY_END        |0xD5 |213
-|KEY_CAPS_LOCK  |0xC1 |193
+|KEY_PAGE_UP    |0xD3 |211
+|KEY_PAGE_DOWN  |0xD6 |214
+|KEY_UP_ARROW   |0xDA |218
+|KEY_DOWN_ARROW |0xD9 |217
+|KEY_LEFT_ARROW |0xD8 |216
+|KEY_RIGHT_ARROW |0xD7 |215
+|===
+
+[float]
+==== Escape and function keys
+The library can simulate function keys up to F24, even though few keyboards have the F13… F24 keys.
+
+|===
+|Key	|Hexadecimal value	|Decimal value
+
+|KEY_ESC        |0xB1 |177
 |KEY_F1         |0xC2 |194
 |KEY_F2         |0xC3 |195
 |KEY_F3         |0xC4 |196