bpftool: man: Add missing format argument to command description

The command description was missing the optional argument. Add it there
for consistency with the rest of the commands.

Signed-off-by: Daniel Xu <[email protected]>
Signed-off-by: Andrii Nakryiko <[email protected]>
Reviewed-by: Quentin Monnet <[email protected]>
Link: https://lore.kernel.org/bpf/140402f22fc377fba4c34376b7e1d2eba2c276b1.1734119028.git.dxu@dxuuu.xyz

Author: danobi

docs/bpftool-btf.rst

@@ -43,7 +43,7 @@ bpftool btf { show | list } [id *BTF_ID*]
     that hold open file descriptors (FDs) against BTF objects. On such kernels
     bpftool will automatically emit this information as well.
 
-bpftool btf dump *BTF_SRC*
+bpftool btf dump *BTF_SRC* [format *FORMAT*]
     Dump BTF entries from a given *BTF_SRC*.
 
     When **id** is specified, BTF object with that ID will be loaded and all