[Improve] Add free-text environment and model routing guidance

apps/docs/environments/definition.mdx

@@ -378,14 +378,16 @@ repository has a known trap, state it plainly.
 
 ## Routing rules
 
-Admins can configure natural-language routing rules from **Settings →
-Environments**. Each rule maps a description, such as “Messages sent in the
-hospital-bugs Slack channel,” to an environment or the broad **All repositories**
-workspace.
-
-Rules are guidance rather than exact string matchers. An environment explicitly
-named in a request takes precedence, and a specific rule takes precedence over a
-catch-all default.
+Admins can configure free-text routing guidance from **Settings → Environments**.
+The same guidance can describe environment choices, model preferences, or both.
+For example: “Use the Web environment for frontend work” or “Use the Astra model
+on high reasoning for complicated work or Luna if the task is straightforward.”
+Model-only guidance does not need to name an environment.
+
+Routing guidance is supplemental rather than an exact string matcher. An
+environment or model explicitly named in a request takes precedence. Guidance
+cannot select disabled models, unavailable environments, or override Roomote's
+permissions and system policies.
 
 ## MCP servers