chore: Fix example in dockerfiles/README

diff --git a/dockerfiles/README b/dockerfiles/README
index c7923984d1ffcd148f4112ad611a0e9517a8b4cc..d1de6859b48ec7972e7874f88b71013c61425d27 100644 (file)
--- a/dockerfiles/README
+++ b/dockerfiles/README
@@ -3,7 +3,7 @@ different build environments.
 
 For instance, run something like this to build ccache in Ubuntu 20.04:
 
-    misc/build-in-docker ubuntu-20-focal
+    misc/build-in-docker ubuntu-20.04
 
 The above command will first build the Ubuntu 20.04 Docker image if needed and
 finally build ccache and run the ccache test suite.