GH-95685: Fix rendering of the string documentation (GH-95686) (GH-95701)

There's an extra underlines that messed the rest of the documentation rendering.

Closes #95685
(cherry picked from commit a525f2ada407d6677bf8ca708f104694de0525e4)

Co-authored-by: Mariatta Wijaya <Mariatta@users.noreply.github.com>