Use a placeholder for the action version in README

Author: henryju

README.md

@@ -51,7 +51,7 @@ jobs:
         # Disabling shallow clones is recommended for improving the relevancy of reporting
         fetch-depth: 0
     - name: SonarQube Scan
-      uses: sonarsource/sonarqube-scan-action@v2.0.2
+      uses: sonarsource/sonarqube-scan-action@<action version> # Ex: v2.1.0, See the latest version at https://github.com/marketplace/actions/official-sonarqube-scan
       env:
         SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }}
         SONAR_HOST_URL: ${{ secrets.SONAR_HOST_URL }}
@@ -61,7 +61,7 @@ If your source code file names contain special characters that are not covered b
 
 ```yaml
     - name: SonarQube Scan
-      uses: sonarsource/sonarqube-scan-action@v2.0.2
+      uses: sonarsource/sonarqube-scan-action@<action version> # Ex: v2.1.0, See the latest version at https://github.com/marketplace/actions/official-sonarqube-scan
       env:
         SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }}
         SONAR_HOST_URL: ${{ secrets.SONAR_HOST_URL }}
@@ -72,7 +72,7 @@ If your SonarQube server uses a self-signed certificate, you can pass a root cer
 
 ```yaml
     - name: SonarQube Scan
-      uses: sonarsource/sonarqube-scan-action@v2.0.2
+      uses: sonarsource/sonarqube-scan-action@<action version> # Ex: v2.1.0, See the latest version at https://github.com/marketplace/actions/official-sonarqube-scan
       env:
         SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }}
         SONAR_HOST_URL: ${{ secrets.SONAR_HOST_URL }}
@@ -83,7 +83,7 @@ You can change the analysis base directory by using the optional input `projectB
 
 ```yaml
 - name: SonarQube Scan
-  uses: sonarsource/sonarqube-scan-action@v2.0.2
+  uses: sonarsource/sonarqube-scan-action@<action version> # Ex: v2.1.0, See the latest version at https://github.com/marketplace/actions/official-sonarqube-scan
   with:
     projectBaseDir: app/src
 ```
@@ -92,7 +92,7 @@ In case you need to add additional analysis parameters, and you do not wish to s
 
 ```yaml
 - name: SonarQube Scan
-  uses: sonarsource/sonarqube-scan-action@v2.0.2
+  uses: sonarsource/sonarqube-scan-action@<action version> # Ex: v2.1.0, See the latest version at https://github.com/marketplace/actions/official-sonarqube-scan
   with:
     projectBaseDir: app/src
     args: >