Summonerd: use a bit more accurate long help doc string

This uses the correct toggle for phase selection in start, and
demonstrates that initialization is *mandatory* but generating phase1
doesn't have to happen if an external output already exists.

tools/summonerd/src/main.rs

@@ -58,11 +58,12 @@ This tool orchestrates receipt of contributions for bootstrapping
 proof parameters, to be used in the Penumbra genesis event.
 The provided subcommands should be run in the following order:
 
-    1. summonerd init --phase1-root <FILE> (optional)
-    2. summonerd start --phase1 ...
-    3. summonerd transition
-    4. summonerd start
-    5. summonerd export
+    0. summonerd generate-phase1 --output <OUTPUT> (optional)
+    1. summonerd init --phase1-root <FILE> ...
+    2. summonerd start --phase 1 ...
+    3. summonerd transition ...
+    4. summonerd start --phase 2 ...
+    5. summonerd export ...
 
 Each of these stages should be triggered manually by a human
 operating the orchestration.