docs/build_tb: Updated export variables based on Vivado/Vitis version

[IstvanZsSzekely]

PR Description

Current documentation only mentions exporting paths for Vivado/Vitis versions prior to 2025. In the latest release, the paths are changed. Updated documentation to include Vivado/Vitis version 2025 path export along with the previous versions.

PR Type

• Bug fix (change that fixes an issue)
• New feature (change that adds new functionality)
• New test (change that adds new test program and/or testbench)
• Update (change that modifies existing functionality)
• Breaking change (has dependencies in other repositories/testbenches)
• Documentation (change that adds or modifies documentation)

PR Checklist

• I have followed the code style guidelines
• I have performed a self-review of changes
• I have ran all testbenches affected by this PR
• I have commented my code, at least hard-to-understand parts
• I have signed off all commits from this PR
• I have updated the documentation (wiki pages, ReadMe files, Copyright etc)
• I have not introduced new Warnings/Errors on compilation/elaboration/simulation
• I have set the verbosity level to none for the test program

[StancaPop]

Good catch!