[Code scan] Correct the BSD license name in the About page

This issue comes from a Codex global scan of deepmodeling/tbplas at commit 4d3652b3dba8eb930e4869a6d41074f62d703692.

Severity: Medium

The About page says TBPLaS is released under “BSD license 2.0”, but the included license text is the three-clause BSD license, including the non-endorsement clause. The license label is inaccurate and can confuse downstream users reviewing licensing.

Code references:
https://github.com/deepmodeling/tbplas/blob/4d3652b3dba8eb930e4869a6d41074f62d703692/doc/source/about/index.rst#L123-L128
https://github.com/deepmodeling/tbplas/blob/4d3652b3dba8eb930e4869a6d41074f62d703692/LICENSE.rst#L6-L11

Suggested fix: update the About page to identify the license as BSD 3-Clause.