[release-branch.go1.13] doc/go1.13: document fmt's number syntax updates
Fixes #32815
Change-Id: Ia8ac9943a920a056ba7dbc69c1c70fa188f7aca8
Reviewed-on: https://go-review.googlesource.com/c/go/+/191578
Reviewed-by: Robert Griesemer <gri@golang.org>
(cherry picked from commit
9e1c864afe00b3cfba3e09d7c67fc17526db464a)
Reviewed-on: https://go-review.googlesource.com/c/go/+/191738
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Run-TryBot: Andrew Bonventre <andybons@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>