When you click on the hexagonal-grid tag you should reach the page below:
click on the help us create it link and at your reputation you should be able to suggest edits to that tag's wiki and excerpt.
The Approve Tag Wiki Edits privilege only becomes available at a reputation of 5,000.
If you are unable to suggest the edit as I describe then please let us know because a 2010 Q&A here, Tag Wiki Editor Qualifications, indicates that it may need 1,500 reputation, but that is not listed on our privileges page.
Further research suggests that it was changed in 2011: Has there been a change in the tag wiki editing privileges policy?