There are there are three different privileges surrounding tags, granted at different reputation levels published [here](https://serverfault.com/help/privileges?tab=all).  


Different Stack Exchange communities grant privileges at different levels, but currently for ServerFault they are as follows: 


- **300** 
[**create tags**](https://serverfault.com/help/privileges/create-tags) - Add new tags to the site  

- **2500** [**create tag synonyms**](https://serverfault.com/help/privileges/suggest-tag-synonyms) - 
Decide which tags have the same meaning as others

- **5000** [**approve tag wiki edits**](https://serverfault.com/help/privileges/approve-tag-wiki-edits) -
Approve edits to tag wikis made by regular users

Which means that at your 400+ reputation level you have sufficient rep to create new tags. 

There is nothing immediately obvious in the manual at which reputation level  you can start editing tag wiki's, but maybe that privilege is included  with the [edit community wiki](https://serverfault.com/help/privileges/edit-community-wiki) privilege, granted at 100 points.  

I *think* that implied in the [**approve tag wiki edits**](https://serverfault.com/help/privileges/approve-tag-wiki-edits) privilege is that edits from users with a rep below 5000 reputation need their tag wiki edits to be reviewed before they become visible.  

The number of active reviewers on ServerFault is quite low (I'm no longer one of them either) so edits might be pending for quite a long time. 

For instance the relatively new <kbd>SLES15</kbd> tag https://serverfault.com/tags/sles15/info currently shows 

[![new sles15 tag][1]][1]



----

Once I hit the <kbd>Edit Pending</kbd> button I see the review option and your suggested edit: 

[![review queue][2]][2]


  [1]: https://i.sstatic.net/65tnHO6B.png
  [2]: https://i.sstatic.net/42NJEkLj.png