bug#68871: Can't use od to print half-precision floats

[Paul Eggert]

Thanks. One minor comment about this:

+@item B
+brain 16 bit float
+@item H
+half precision float

It might be helpful explain these two formats, e.g., to cite:

https://en.wikipedia.org/wiki/Bfloat16_floating-point_format

and

https://en.wikipedia.org/wiki/Half-precision_floating-point_format

respectively, since the formats are new compared to the other formats 
being discussed.