all: consistently use "IEEE 754" over "IEEE-754"

all: consistently use "IEEE 754" over "IEEE-754"

There is no hyphen between the organization and the number.

For example, https://standards.ieee.org/ieee/754/6210/
shows the string "IEEE 754-2019" and not "IEEE-754-2019".

This assists in searching for "IEEE 754" in documentation
and not missing those using "IEEE-754".

Change-Id: I9a50ede807984ff1e2f17390bc1039f6a5d162e5
Reviewed-on: https://go-review.googlesource.com/c/go/+/575438
Run-TryBot: Joseph Tsai <joetsai@digital-static.net>
Reviewed-by: Robert Griesemer <gri@google.com>
Auto-Submit: Joseph Tsai <joetsai@digital-static.net>
TryBot-Result: Gopher Robot <gobot@golang.org>
TryBot-Bypass: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>