more java versions & latest version in readme

.github/workflows/build.yml

@@ -27,4 +27,4 @@ jobs:
           git config --global user.name "Github Actions"
           ./waterfall p
       - name: build
-        run: mvn clean install javadoc:javadoc -B
+        run: mvn clean install javadoc:javadoc -B

README.md

@@ -40,13 +40,14 @@ Waterfall requires **Java 8** or above.
 <dependency>
     <groupId>io.github.waterfallmc</groupId>
     <artifactId>waterfall-api</artifactId>
-    <version>1.19-R0.1-SNAPSHOT</version>
+    <version>1.20-R0.2-SNAPSHOT</version>
     <scope>provided</scope>
 </dependency>
  ```
 
 **Or alternatively, with Gradle:**
 
+Groovy
  * Repository:
 ```groovy
 repositories {
@@ -58,7 +59,7 @@ repositories {
  * Artifact:
 ```groovy
 dependencies {
-    compileOnly 'io.github.waterfallmc:waterfall-api:1.19-R0.1-SNAPSHOT'
+    compileOnly 'io.github.waterfallmc:waterfall-api:1.20-R0.2-SNAPSHOT'
 }
 ```