top: eliminate all field numbers from the man document

top: eliminate all field numbers from the man document

As far back as release 3.2.8 (maybe even farther) this
man page used a number with each field's descriptions.

That practice caused no real harm when top was limited
to a grand total of 26 fields (thru lower case letters
of the alphabet). However, now we've reached 70 fields
and, depending on the name that's chosen, adding a new
field could result in a massive renumbering of fields.

Thus, this patch eliminates such potential by removing
all numbers from section '3a. DESCRIPTIONS of Fields'.

Signed-off-by: Jim Warner <james.warner@comcast.net>