Update logos/README.md

Co-authored-by: Hugo van Kemenade <[email protected]>

Author: arp242

logos/README.md

@@ -11,7 +11,7 @@ file.
 The color versions are intended for a white background, while the reverse
 versions are intended for a black background. The fallback versions were
 designed for when the background cannot be controlled, such as in GitHub
-`readme.md` files where the background depends on the user's dark or light theme
+`README.md` files where the background depends on the user's dark or light theme
 preferences.
 
 ![toml-logos-list](./show/logos-list.png)