Update README.md

v2.315.0

Signed-off-by: DerSkythe <31771569+derskythe@users.noreply.github.com>

Author: derskythe

README.md

@@ -43,7 +43,7 @@ This is a [fork](https://github.com/myoung34/docker-github-actions-runner).
 ## Tag convention
 
 For example:
-`ubuntu-bionic-2.313.0-31.1`
+`ubuntu-bionic-2.315.0-31.1`
 
 The tag consists entirely of the following parts: