generate a man page as part of the build

Cargo.lock

@@ -114,6 +114,16 @@ dependencies = [
  "os_str_bytes",
 ]
 
+[[package]]
+name = "clap_mangen"
+version = "0.1.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "105180c05a72388d5f5e4e4f6c79eecb92497bda749fa8f963a16647c5d5377f"
+dependencies = [
+ "clap",
+ "roff",
+]
+
 [[package]]
 name = "config-file"
 version = "0.2.3"
@@ -217,6 +227,7 @@ dependencies = [
  "atty",
  "clap",
  "clap_complete",
+ "clap_mangen",
  "config-file",
  "directories",
  "lscolors",
@@ -543,6 +554,12 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "roff"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b833d8d034ea094b1ea68aa6d5c740e0d04bad9d16568d08ba6f76823a114316"
+
 [[package]]
 name = "rustix"
 version = "0.36.7"