[GR-58699] Improve documentation for the sandbox.UseLowMemoryTrigger option.

PullRequest: graal/18971

Author: jchalou

docs/security/polyglot-sandbox.md

@@ -349,7 +349,7 @@ The allocated bytes are checked by a separate high-priority thread that will be
 There is one such thread for each memory-limited context (one with `sandbox.MaxHeapMemory` set).
 The retained bytes computation is done by yet another high-priority thread that is started from the allocated bytes checking thread as needed.
 The retained bytes computation thread also cancels the context if the heap memory limit is exceeded.
-Additionally, when the low memory trigger is invoked, all contexts on engines with at least one memory-limited context are paused together with their allocation checkers.
+Additionally, when the low memory trigger is invoked, all memory-limited contexts are paused together with their allocation checkers.
 All individual retained size computations are canceled.
 Retained bytes in the heap for each memory-limited context are computed by a single high-priority thread.
 
@@ -390,7 +390,7 @@ The described low memory trigger can be disabled by the `sandbox.UseLowMemoryTri
 By default it is enabled ("true"). If disabled ("false"), retained size checking for the execution context can be triggered only by the allocated bytes checker.
 All contexts using the `sandbox.MaxHeapMemory` option must use the same value for `sandbox.UseLowMemoryTrigger`.
 
-The `sandbox.UseLowMemoryTrigger` option is not supported for the ISOLATED and UNTRUSTED sandbox policies. The option defaults to disabled (`false`) wherever it is not supported.
+The `sandbox.UseLowMemoryTrigger` option is not supported for the ISOLATED and UNTRUSTED sandbox policies as the polyglot engine runs in a `native-image` isolate for those policies. It is also not supported on a `native-image` host regardless of the policy. The option defaults to disabled (`false`) wherever it is not supported.
 
 ### Limiting the Amount of Data Written to Standard Output and Error Streams