docs: rename example jq utility to total

Apparently sum(1) is a BSD and GNU coreutil used to compute the
"16-bit BSD checksum" of a file.

docs/content/manual/manual.yml

@@ -3571,8 +3571,8 @@ sections:
  when writing the "shebang" for a jq script:
 
  #!/bin/sh --
- # sum - Output the sum of the given arguments (or stdin)
- # usage: sum [numbers...]
+ # total - Output the sum of the given arguments (or stdin)
+ # usage: total [numbers...]
  # \
  exec jq --args -MRnf "$0" -- "$@"
 
@@ -3585,16 +3585,16 @@ sections:
  . as $dot |
  try tonumber catch false |
  if not or isnan then
- @json "sum: Invalid number \($dot).\n" | halt_error(1)
+ @json "total: Invalid number \($dot).\n" | halt_error(1)
  end
  ) as $n (0; . + $n)
 
  The `exec` line is considered a comment by jq, so it is ignored.
  But it is not ignored by `sh`, since in `sh` a backslash at the
  end of the line does not continue the comment.
- With this trick, when the script is invoked as `sum 1 2`,
- `/bin/sh -- /path/to/sum 1 2` will be run, and `sh` will then
- run `exec jq --args -MRnf /path/to/sum -- 1 2` replacing itself
+ With this trick, when the script is invoked as `total 1 2`,
+ `/bin/sh -- /path/to/total 1 2` will be run, and `sh` will then
+ run `exec jq --args -MRnf /path/to/total -- 1 2` replacing itself
  with a `jq` interpreter invoked with the specified options (`-M`,
  `-R`, `-n`, `--args`), that evaluates the current file (`$0`),
  with the arguments (`$@`) that were passed to `sh`.