truncate docs version to major.minor (#89)
The version extracted from version.go was used as-is (e.g., 1.1.4),
creating separate patch-level entries in the MkDocs version menu.
Java and Python already truncate to major.minor via cut/split. Apply
the same truncation so the version menu shows only major.minor entries.
use GitHub App token for bump PR to trigger CI (#91)
PRs created by GITHUB_TOKEN do not trigger workflow runs (GitHub
security limitation). Replace with a GitHub App installation token
so CI runs automatically on bump PRs.