README update and build step name typo fix.

.woodpecker/test_build.yaml

@@ -3,7 +3,7 @@ when:
   - event: [push, tag, manual]
 
 steps:
-  - name: "Build containers without pushing"
+  - name: "Build container without pushing"
     image: code.pztrn.name/containers/mirror/docker:26.1.1-dind
     privileged: true
     commands:

README.md

@@ -2,6 +2,13 @@
 
 This is a Redmine container I'm using.
 
+Versioning is using Redmine version with `-X` appendix when Redmine version stays same but plugins were updated.
+
+E.g.:
+
+- `code.pztrn.name/containers/redmine:5.1.12` - first Redmine 5.1.12 build.
+- `code.pztrn.name/containers/redmine:5.1.12-4` - fourth plugins update for Redmine 5.1.12.
+
 ## What is in container
 
 ### Base