Update getting-started.md to specify java version

[arifcse019]

Without java 17, gradle builds fails

I got the following error when using Java 11 on Ubuntu 22

`ubuntu@ip-172-31-53-138:~/java-simple$ gradle assemble
Starting a Gradle Daemon (subsequent builds will be faster)

FAILURE: Build failed with an exception.

• What went wrong:
  A problem occurred configuring root project 'java-simple'.

Could not resolve all files for configuration ':classpath'.
Could not resolve org.springframework.boot:spring-boot-gradle-plugin:3.0.6.
Required by:
project : > org.springframework.boot:org.springframework.boot.gradle.plugin:3.0.6
> No matching variant of org.springframework.boot:spring-boot-gradle-plugin:3.0.6 was found. The consumer was configured to find a library for use during runtime, compatible with Java 11, packaged as a jar, and its dependencies declared externally, as well as attribute 'org.gradle.plugin.api-version' with value '8.5' but:
- Variant 'apiElements' capability org.springframework.boot:spring-boot-gradle-plugin:3.0.6 declares a library, packaged as a jar, and its dependencies declared externally:
- Incompatible because this component declares a component for use during compile-time, compatible with Java 17 and the consumer needed a component for use during runtime, compatible with Java 11
- Other compatible attribute:
- Doesn't say anything about org.gradle.plugin.api-version (required '8.5')
- Variant 'javadocElements' capability org.springframework.boot:spring-boot-gradle-plugin:3.0.6 declares a component for use during runtime, and its dependencies declared externally:
- Incompatible because this component declares documentation and the consumer needed a library
- Other compatible attributes:
- Doesn't say anything about its target Java version (required compatibility with Java 11)
- Doesn't say anything about its elements (required them packaged as a jar)
- Doesn't say anything about org.gradle.plugin.api-version (required '8.5')
- Variant 'mavenOptionalApiElements' capability org.springframework.boot:spring-boot-gradle-plugin-maven-optional:3.0.6 declares a library, packaged as a jar, and its dependencies declared externally:
- Incompatible because this component declares a component for use during compile-time, compatible with Java 17 and the consumer needed a component for use during runtime, compatible with Java 11
- Other compatible attribute:
- Doesn't say anything about org.gradle.plugin.api-version (required '8.5')
- Variant 'mavenOptionalRuntimeElements' capability org.springframework.boot:spring-boot-gradle-plugin-maven-optional:3.0.6 declares a library for use during runtime, packaged as a jar, and its dependencies declared externally:
- Incompatible because this component declares a component, compatible with Java 17 and the consumer needed a component, compatible with Java 11
- Other compatible attribute:
- Doesn't say anything about org.gradle.plugin.api-version (required '8.5')
- Variant 'runtimeElements' capability org.springframework.boot:spring-boot-gradle-plugin:3.0.6 declares a library for use during runtime, packaged as a jar, and its dependencies declared externally:
- Incompatible because this component declares a component, compatible with Java 17 and the consumer needed a component, compatible with Java 11
- Other compatible attribute:
- Doesn't say anything about org.gradle.plugin.api-version (required '8.5')
- Variant 'sourcesElements' capability org.springframework.boot:spring-boot-gradle-plugin:3.0.6 declares a component for use during runtime, and its dependencies declared externally:
- Incompatible because this component declares documentation and the consumer needed a library
- Other compatible attributes:
- Doesn't say anything about its target Java version (required compatibility with Java 11)
- Doesn't say anything about its elements (required them packaged as a jar)
- Doesn't say anything about org.gradle.plugin.api-version (required '8.5')

• Try:

Run with --stacktrace option to get the stack trace.
Run with --info or --debug option to get more log output.
Run with --scan to get full insights.
Get more help at https://help.gradle.org.

BUILD FAILED in 53s
`

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: arifcse019 / name: Arif Akram Khan (490c1c0)
• ✅ login: cartermp / name: Phillip Carter (9c58ad8)
• ✅ login: svrnm / name: Severin Neumann (ba994f8)

[svrnm]

thanks @arifcse019

@open-telemetry/java-approvers PTAL!