Fixed a comparison operator

- Added a less than or equal to comaprison operator in the check of the
string size vs its capacity. If the operator is <, then errors are
thrown in the case where the string is fully loaded.

inc/Message.hpp

@@ -437,7 +437,7 @@ template<const size_t SIZE>
 inline void Message::appendString(const String<SIZE> & string) {
 	assertI(dataSize + string.size() < ECSS_MAX_MESSAGE_SIZE, ErrorHandler::MessageTooLarge);
 	// TODO: Do we need to keep this check? How does etl::string handle it?
-	assertI(string.size() < string.capacity(), ErrorHandler::StringTooLarge);
+	assertI(string.size() <= string.capacity(), ErrorHandler::StringTooLarge);
 
 	memcpy(data + dataSize, string.data(), string.size());