Fix GitHub Actions to use short SHA for image tags

- Use first 7 characters of commit SHA instead of full SHA
- Update docker metadata action to use format=short for SHA tags
- Update documentation examples to show short SHA format
- Image tags will now be: develop-6e3fce0 instead of develop-6e3fce0cbe8660e3bc972d4a5d936808d4e1bb35

This makes image tags more readable and follows common Git conventions.

Author: mariusgeorgescu

.github/README.md

@@ -13,8 +13,8 @@ Automatically builds and publishes Docker images to Docker Hub when code is push
 - Pull requests to `main` or `develop` branches
 
 **Image Tags:**
-- `main-<commit-sha>` - For main branch commits
-- `develop-<commit-sha>` - For develop branch commits  
+- `main-<short-sha>` - For main branch commits (e.g., `main-6e3fce0`)
+- `develop-<short-sha>` - For develop branch commits (e.g., `develop-6e3fce0`)
 - `latest` - For main branch (default branch)
 - `pr-<pr-number>` - For pull requests
 
@@ -35,10 +35,10 @@ Images are automatically built and published. To use a specific version:
 docker pull mariusgeorgescu/bjj-dapp-web:latest
 
 # Specific commit
-docker pull mariusgeorgescu/bjj-dapp-web:main-abc1234
+docker pull mariusgeorgescu/bjj-dapp-web:main-6e3fce0
 
 # Develop branch
-docker pull mariusgeorgescu/bjj-dapp-web:develop-xyz5678
+docker pull mariusgeorgescu/bjj-dapp-web:develop-6e3fce0
 ```
 
 ## Configuration

.github/workflows/docker-build.yml

@@ -43,7 +43,7 @@ jobs:
           tags: |
             type=ref,event=branch
             type=ref,event=pr
-            type=sha,prefix={{branch}}-
+            type=sha,prefix={{branch}}-,format=short
             type=raw,value=latest,enable={{is_default_branch}}
 
       - name: Build and push Docker image
@@ -75,11 +75,12 @@ jobs:
       - name: Extract image tag
         id: image-tag
         run: |
+          SHORT_SHA=$(echo "${{ github.sha }}" | cut -c1-7)
           if [[ "${{ github.ref }}" == "refs/heads/main" ]]; then
-            echo "tag=main-${{ github.sha }}" >> $GITHUB_OUTPUT
+            echo "tag=main-${SHORT_SHA}" >> $GITHUB_OUTPUT
             echo "branch=main" >> $GITHUB_OUTPUT
           else
-            echo "tag=develop-${{ github.sha }}" >> $GITHUB_OUTPUT
+            echo "tag=develop-${SHORT_SHA}" >> $GITHUB_OUTPUT
             echo "branch=develop" >> $GITHUB_OUTPUT
           fi