DOC: some stylistic improvements to docstring rendering in documentation
DOC: correction of example in unstack docstring
CI: allow print_versions to work without pandas install
Merge pull request #4776 from jorisvandenbossche/doc-unstack

DOC: correction of example in unstack docstring
Merge pull request #4901 from cpcloud/print-versions-without-pandas

CI: allow print_versions to work without pandas install
Merge pull request #4775 from jorisvandenbossche/docstring-rendering

DOC: some stylistic improvements to docstring rendering in documentation