#315: fix self-contradicting javadoc left by the previous commit

FixedPlacementPolicy's class javadoc still opened with "This ignores caps
and reachability" after the previous commit added reachability as the
fourth carve-out that is explicitly NOT ignored — caught by a shape-check
survey run against this same file as part of #315's own request ("look in
placement/ ... for the same shape: a caller/comment that documents an
expectation ... where an implementation does not meet it"). Reworded the
opening sentence: fixed still ignores caps (maxLoad) by design, but
reachability is now a narrower, per-call retry exclusion, not an ignored
concern.

fleetd/src/main/java/dev/ltms/fleet/placement/FixedPlacementPolicy.java

@@ -5,8 +5,12 @@ import java.util.List;
 
 /**
  * Backward-compatible placement: an unqualified spawn always resolves to the configured default
- * profile, exactly as {@code CompositePeerLauncher} did before CB-518. This ignores caps and
- * reachability so that a pre-existing config behaves identically after upgrade.
+ * profile, exactly as {@code CompositePeerLauncher} did before CB-518. This ignores caps
+ * ({@code maxLoad}) so that a pre-existing config behaves identically after upgrade — capacity
+ * gating for automatic placement is deliberately out of scope for {@code fixed}, exactly as it
+ * always has been. Reachability is a narrower exception (fleetd #315, below): a profile is never
+ * checked for reachability up front, only skipped once it has already failed in <em>this same</em>
+ * spawn call's retry loop — see the unreachable case below.
  *
  * <p>Four exceptions walk past the default instead of returning it unconditionally:
  * <ul>