docs(exec): clarify command ordering and output grouping for -x/--exec

doc/fd.1

@@ -448,13 +448,13 @@ Note that all subsequent positional arguments are considered to be arguments to
 It is therefore recommended to place the \-x/\-\-exec option last. Alternatively, you can supply
 a ';' argument to end the argument list and continue with more fd options.
 Most shells require ';' to be escaped: '\\;'.
-This option can be specified multiple times, in which case all commands are run for each
-file found, in the order they are provided. In that case, you must supply a ';' argument for
-all but the last commands.
+This option can be specified multiple times. Commands for the same search result run sequentially
+in the order they are given. In that case, you must supply a ';' argument for all but the last command.
+When running in parallel, fd buffers command output and prints it together for each search result,
+without interleaving it with command output for other results.
 
-If parallelism is enabled, the order commands will be executed in is non-deterministic. And even with
---threads=1, the order is determined by the operating system and may not be what you expect. Thus, it is
-recommended that you don't rely on any ordering of the results.
+The order in which different search results are processed and their output is printed is not
+guaranteed, even with --threads=1.
 
 Before executing the command, any placeholder patterns in the command are replaced with the
 corresponding values for the current file. The same placeholders are used as in the "\-\-format"

src/cli.rs

@@ -895,10 +895,14 @@ impl clap::Args for Exec {
                 .help("Execute a command for each search result")
                 .long_help(
                     "Execute a command for each search result in parallel (use --threads=1 for sequential command execution). \
-                     There is no guarantee of the order commands are executed in, and the order should not be depended upon. \
+                     The order in which different search results are processed and their output is printed is not guaranteed, even with --threads=1. \
                      All positional arguments following --exec are considered to be arguments to the command - not to fd. \
                      It is therefore recommended to place the '-x'/'--exec' option last. \
-                     Use '\\;' to terminate the command template if you need to continue passing fd arguments afterwards.\n\
+                     Use '\\;' to terminate the command template if you need to continue passing fd arguments afterwards.\n\n\
+                     This option can be specified multiple times. Commands for the same search result run sequentially in the order they are given. \
+                     Terminate each command except the last with '\\;'. \
+                     When running in parallel, fd buffers command output and prints it together for each search result, \
+                     without interleaving it with command output for other results.\n\n\
                      The following placeholders are substituted before the command is executed:\n  \
                        '{}':   path (of the current search result)\n  \
                        '{/}':  basename\n  \