Update readme.md

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: He-Pin

readme.md

@@ -305,7 +305,7 @@ To run the tests:
 ./mill 'sjsonnet.jvm[3.3.7]'.test
 ```
 
-If you want test for all platforms and versions, you can run
+If you want to test for all platforms and versions, you can run
 
 ```bash
 ./mill __.test