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`.

modules/webxr/register_types.cpp

@@ -57,7 +57,7 @@ void uninitialize_webxr_module(ModuleInitializationLevel p_level) {
 
 #ifdef WEB_ENABLED
 	if (webxr.is_valid()) {
-		// uninitialise our interface if it is initialised
+		// uninitialize our interface if it is initialized
 		if (webxr->is_initialized()) {
 			webxr->uninitialize();
 		}