fix(mangen): Prefer the bin_name for the synopsis

Use the user-supplied bin_name over the command name for the synopsis.
This presents a sample invocation more in line with how the CLI will
be used.

clap_mangen/src/render.rs

@@ -29,7 +29,10 @@ pub(crate) fn description(roff: &mut Roff, cmd: &clap::Command) {
 }
 
 pub(crate) fn synopsis(roff: &mut Roff, cmd: &clap::Command) {
-    let mut line = vec![bold(cmd.get_name()), roman(" ")];
+    let mut line = vec![
+        bold(cmd.get_bin_name().unwrap_or_else(|| cmd.get_name())),
+        roman(" "),
+    ];
 
     for opt in cmd.get_arguments().filter(|i| !i.is_hide_set()) {
         let (lhs, rhs) = option_markers(opt);