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/mbedtls/stream_peer_mbedtls.cpp

@@ -242,7 +242,7 @@ void StreamPeerMbedTLS::poll() {
 		return;
 	}
 
-	// We could pass nullptr as second parameter, but some behaviour sanitizers don't seem to like that.
+	// We could pass nullptr as second parameter, but some behavior sanitizers don't seem to like that.
 	// Passing a 1 byte buffer to workaround it.
 	uint8_t byte;
 	int ret = mbedtls_ssl_read(tls_ctx->get_context(), &byte, 0);