Avoid using markdown, keep it natural. Make sure all information is accurate. Also, note that Rockstar Games does patch notes on their official site; maybe the user wants those. If the user is experiencing issues with an older version, advising them to update through official channels is the best approach.
I should also mention that the 2015 update was significant because it allowed cross-play between PC, PS4, and Xbox One. So, confirming that Update 1-2015 brought PC in line with the next-gen consoles' features. Avoid using markdown, keep it natural
Additionally, the user might be confused about where to get the update. The answer should direct them to check for updates via the in-game prompt or through Steam's update system. Emphasize legal acquisition. Avoid using markdown