Add note about valid Java package name for groupID

[bohnertchris]

CQDOC-18946

Added note to README.md about valid Java package name for groupID

Description

See above

Related Issue

CQDOC-18946

Motivation and Context

It was a good suggestion from a reader. AdobeDocs/experience-manager-core-components.en#31

How Has This Been Tested?

Same change passed MD validation in our public docs. See PR#214 on the Core Components repo.

Screenshots (if appropriate):

None

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation change
• [ ]

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[kwin]

You should adjust the regex in

aem-project-archetype/src/main/resources/META-INF/maven/archetype-metadata.xml

Line 35 in a646119

<validationRegex>^[a-zA-Z0-9\.\-_]+$</validationRegex>

accordingly to enforce this constraint

[bpauli]

@kwin Thank you for hands up. The regex got adjusted in 544a011