Some package body docs refer to package declaration instead of package body

[JHertz5]

Environment v3.27.0

Describe the bug There are some mistakes the package body rule docs, where the code snippet or rule description refers to package declaration rather than package body

• https://vhdl-style-guide.readthedocs.io/en/3.27.0/package_body_rules.html#package-body-502
• https://vhdl-style-guide.readthedocs.io/en/3.27.0/package_body_rules.html#package-body-503
• https://vhdl-style-guide.readthedocs.io/en/3.27.0/package_body_rules.html#package-body-504
• https://vhdl-style-guide.readthedocs.io/en/3.27.0/package_body_rules.html#package-body-507

[JHertz5]

I've raised PR #1297 to address this issue.