Clarify -f argument parsing (#3199)

docs/content/manual/dev/manual.yml

@@ -221,10 +221,11 @@ sections:
         RS.  This mode also parses the output of jq without the `--seq`
         option.
 
-      * `-f filename` / `--from-file filename`:
+      * `-f` / `--from-file`:
 
-        Read filter from the file rather than from a command line, like
-        awk's -f option.
+        Read the filter from a file rather than from a command line,
+        like awk's -f option. This changes the filter argument to be
+        interpreted as a filename, instead of the source of a program.
 
       * `-L directory` / `--library-path directory`:
 
@@ -3633,7 +3634,7 @@ sections:
           # total - Output the sum of the given arguments (or stdin)
           # usage: total [numbers...]
           # \
-          exec jq --args -MRnf "$0" -- "$@"
+          exec jq --args -MRnf -- "$0" "$@"
 
           $ARGS.positional |
           reduce (
@@ -3653,7 +3654,7 @@ sections:
       end of the line does not continue the comment.
       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
+      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`.

src/main.c

@@ -94,7 +94,7 @@ static void usage(int code, int keep_it_short) {
       "      --stream-errors       implies --stream and report parse error as\n"
       "                            an array;\n"
       "      --seq                 parse input/output as application/json-seq;\n"
-      "  -f, --from-file file      load filter from the file;\n"
+      "  -f, --from-file           load the filter from a file;\n"
       "  -L, --library-path dir    search modules from the directory;\n"
       "      --arg name value      set $name to the string value;\n"
       "      --argjson name value  set $name to the JSON value;\n"