Document Maven Plugin in Java Docs

[adinauer]

Description

https://docs.sentry.io/platforms/java/ should show usage of the Maven Plugin instead of a Maven dependency, same as inproduct docs already do.

[adinauer]

Also change "Groovy" to "Gradle" in source example tab titles

[lcian]

Also change "Groovy" to "Gradle" in source example tab titles

At the moment the sources are valid for Groovy build.gradle files e.g.

id "io.sentry.jvm.gradle" version "5.2.0"

is valid for build.gradle but for build.gradle.kts it should be changed to

id("io.sentry.jvm.gradle") version "5.2.0"

Instead of replacing it, we could add a new tab Gradle with the build.gradle.kts version. What do you think? @adinauer

[adinauer]

Yeah we can do that. Eventually we should take a stab at creating a wizard.