fleetd #453: point the new javadoc at the right javadoc

#456's first paragraph said "HerdrPeerLauncher's own {@link
#spawn(SpawnRequest, PlacementDecision)} javadoc". That link resolves to this
interface's own abstract declaration, not to HerdrPeerLauncher's override, so a
reader who follows it lands on the wrong text. The second paragraph already
used the plain {@code HerdrPeerLauncher.spawn(...)} form; both now match.

Also says who is actually forced to read the paragraph, because #456's
reasoning rests on it and the two cases differ. A class that implements this
interface directly must write a body for spawn(SpawnRequest,
PlacementDecision) - it is abstract here - so it reads this javadoc. A
subclass of HerdrPeerLauncher does not: HerdrPeerLauncher already implements
that method (member/HerdrPeerLauncher.java:611) and the subclass inherits the
body. For a subclass the paragraph is advice, not a gate.

javadoc -Ddoclint=reference: 5 "reference not found", the same 5 in the same 5
untouched files as origin/main at 2af13ab, and none in PeerLauncher.java. Those
5 are ticket #459. mvn compile rc=0.

fleetd/src/main/java/dev/ltms/fleet/peer/PeerLauncher.java

@@ -175,9 +175,16 @@ public interface PeerLauncher {
      * correct to do so. But it stays correct only as long as that holds: <strong>if a launcher ever
      * routes more than one profile per role, it MUST override this method</strong>, or every role
      * silently resolves to {@link #defaultProfile()} with no error and no log line. {@code
-     * HerdrPeerLauncher}'s own {@link #spawn(SpawnRequest, PlacementDecision)} javadoc names this
-     * method and {@link #place} explicitly as "unoverridden here" for exactly this reason — read
-     * that javadoc before adding role-pool routing to any {@code HerdrPeerLauncher} subclass.
+     * HerdrPeerLauncher.spawn(SpawnRequest, PlacementDecision)} — the override in {@code
+     * dev.ltms.fleet.member}, not the declaration below — names this method and {@link #place}
+     * explicitly as "unoverridden here" for exactly this reason. Read it before adding role-pool
+     * routing to any {@code HerdrPeerLauncher} subclass.
+     *
+     * <p>Who is forced to read which paragraph, because it is not symmetric. A new class that
+     * implements this interface directly must write a body for {@link #spawn(SpawnRequest,
+     * PlacementDecision)}, which is abstract here, so it lands on this javadoc. A subclass of
+     * {@code HerdrPeerLauncher} does not: that class already implements the method, and the
+     * subclass inherits the body. So for a subclass this paragraph is advice, not a gate.
      */
     default String defaultProfileFor(MemberRole role) {
         return defaultProfile();