Add a description of the Jakarta EE namespace in the documentation for Spring Boot

[linghengqian]

Fixes #21476.

Changes proposed in this pull request:

• Add a description of the Jakarta EE namespace in the documentation for Spring Boot.
• For Transition from Java EE to Jakarta EE #26041 .

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[linghengqian]

• @taojintianxia It looks like a Apache ShardingSphere Committer is required to perform the approve operation, I can't approve my own PR.

[RaigorJiang]

Merged, thank you!