docs(readme): correct spelling mistake of Teespring

Signed-off-by: Mark <remarkablemark@users.noreply.github.com>

Author: remarkablemark

README.md

@@ -567,7 +567,7 @@ Support this project with your organization. Your logo will show up here with a
 - [Patreon](https://b.remarkabl.org/patreon)
 - [Ko-fi](https://b.remarkabl.org/ko-fi)
 - [Liberapay](https://b.remarkabl.org/liberapay)
-- [Teepsring](https://b.remarkabl.org/teespring)
+- [Teespring](https://b.remarkabl.org/teespring)
 
 ## License