docs: the roster pages use contractions and the active voice

docs/4-implementation/agent-state/roster.md

@@ -1,6 +1,6 @@
 # Agent roster: topology file and manager behaviour
 
-The hive-local `topology.json`, how it is derived, and what is special about the
+The hive-local `topology.json`, how the hive derives it, and what's special about the
 manager (`ruth`). The operator's overview is
 [the agent roster page](../../2-handbook/agents/agent-roster.md).
 

docs/README.md

@@ -99,7 +99,7 @@ One agent: its roster entry, state, config and page. Start at
   [`4-implementation/agent-state/persistence.md`](4-implementation/agent-state/persistence.md).
 - **Who can do what to whom — the agent roster and privilege?** →
   [`2-handbook/agents/agent-roster.md`](2-handbook/agents/agent-roster.md); how
-  `topology.json` is rebuilt and what is special about the manager:
+  `topology.json` is rebuilt and what's special about the manager:
   [`4-implementation/agent-state/roster.md`](4-implementation/agent-state/roster.md).
 - **What does an agent's own page show?** →
   [`2-handbook/agents/web-page.md`](2-handbook/agents/web-page.md); the full