chore: add missing language to a code block

https://github.com/open-feature/openfeature.dev/actions/runs/6409684934/job/17401385920?pr=220

MD040/fenced-code-language Fenced code blocks should have a language specified

Signed-off-by: Michael Beemer <[email protected]>

Author: beeme1mr

README.md

@@ -65,7 +65,7 @@ dependencies {
 ```
 <!-- x-release-please-end -->
 Please note that the `version` can be any `Commit SHA` or a version based on a branch as follows:
-```
+```sh
 api("com.github.open-feature:kotlin-sdk:[ANY_BRANCH]-SNAPSHOT")
 ```