gh-100428: Make float documentation more accurate (GH-100437)

Previously, the grammar did not accept `float("10")`.
Also implement mdickinson's suggestion of removing the indirection.
(cherry picked from commit 2e1a9ce9890aba748a518a39d01d1ea6d623d0d9)

Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>