Style: Misc docs and comment style and language fixes

- Removed empty paragraphs in XML.
- Consistently use bold style for "Example:", on a new line.
- Fix usage of `[code]` when hyperlinks could be used (`[member]`, `[constant]`).
- Fix invalid usage of backticks for inline code in BBCode.
- Fix some American/British English spelling inconsistencies.
- Other minor fixes spotted along the way, including typo fixes with codespell.
- Don't specify `@GlobalScope` for `enum` and `constant`.

drivers/alsamidi/midi_driver_alsamidi.cpp

@@ -43,7 +43,7 @@ MIDIDriverALSAMidi::MessageCategory MIDIDriverALSAMidi::msg_category(uint8_t msg
 	} else if (msg_part >= 0xf0) {
 		// System Exclusive begin/end are specified as System Common Category messages,
 		// but we separate them here and give them their own categories as their
-		// behaviour is significantly different.
+		// behavior is significantly different.
 		if (msg_part == 0xf0) {
 			return MessageCategory::SysExBegin;
 		} else if (msg_part == 0xf7) {