Updated PR guidelines & added GitHub workflow build file

.github/workflows/build.yml

@@ -0,0 +1,36 @@
+name: Build
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    types: [opened, synchronize, reopened]
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0  # Shallow clones should be disabled for a better relevancy of analysis
+      - name: Set up JDK 8
+        uses: actions/setup-java@v1
+        with:
+          java-version: 8
+      - name: Cache SonarCloud packages
+        uses: actions/cache@v1
+        with:
+          path: ~/.sonar/cache
+          key: ${{ runner.os }}-sonar
+          restore-keys: ${{ runner.os }}-sonar
+      - name: Cache Maven packages
+        uses: actions/cache@v1
+        with:
+          path: ~/.m2
+          key: ${{ runner.os }}-m2-${{ hashFiles('**/pom.xml') }}
+          restore-keys: ${{ runner.os }}-m2
+      - name: Build and analyze
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}  # Needed to get PR information, if any
+          SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }}
+        run: mvn -B verify org.sonarsource.scanner.maven:sonar-maven-plugin:sonar -Dsonar.projectKey=PlayPro_CoreProtect -Dsonar.organization=playpro -Dsonar.host.url=https://sonarcloud.io

CONTRIBUTING.md

@@ -11,6 +11,7 @@ Please note we have a code of conduct, please follow it in all your interactions
 - Use descriptiveCamelCase for variable/method names. Names containing underscore or abbreviations should be changed.
 - Restrict changes in a commit to a single event or section of code (e.g. refactor BlockBreakEvent and BlockPlaceEvent in separate commits)
 - Attempt to keep the amount of code modified in a single commit small and readable. 
+- Please utilize [SonarLint](https://www.sonarlint.org) in your IDE. Contributions are automatically analyzed.
 - When adding new functionality, please also be sure to update the documentation as well.
 - Use common sense. If you have a suggestion for a contribution guideline, post it on Discord.