docs: add cidr_block to attribute reference of aws_vpc

[stefanfreitag]

Description

Added the missing cidr_block field in the attribute reference section.

Additionally,

• re-ordered attributes in the attribute reference section alphabetically
• changed in the argument reference section the format of three default values from plain text to code style.

Relations

Closes #38034 .

References

none

Output from Acceptance Testing

Not applicable as only documentation is updated by this pull request.