Update Java template to print "Hello World" with proper capitalization

[Flotss]

This pull request updates the Java template in IntelliJ Community to print the "Hello World" message with proper capitalization. Currently, the template uses the lowercase "Hello world" format, which is inconsistent with the standard convention.

The proposed changes modify the Java template code to reflect the correct capitalization by using "Hello World" instead of "Hello world". This aligns with the traditional style and improves the clarity and readability of the template for new users.

Please review this pull request and consider merging it into the main branch. This simple adjustment will contribute to a more standardized and professional experience for IntelliJ Community users.

Thank you for your attention to this matter.