update base46 theme url

Author: siduck

src/routes/docs/config/theming.mdx

@@ -66,7 +66,7 @@ M.ui = {
 
 > <u>WARNING: Do this at your own risk because you might not be able to make nice nvchad themes like siduck.</u>
 
-- Default themes can be found in our [`base46`](https://github.com/NvChad/base46) repository.
+- Default themes can be found in our [`base46`](https://github.com/NvChad/base46/tree/v2.5/lua/base46/themes) repository.
 
 Here is the default structure for NvChad themes: