doc: update measure memory rejection information

If in case context is unable to allocate a promise then
`ERR_CONTEXT_NOT_INITIALIZED` error will be thrown (as promise
rejection) in the vm measureMemory call.

PR-URL: #41639
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Debadree Chatterjee <debadree333@gmail.com>

doc/api/vm.md

@@ -1140,8 +1140,9 @@ current V8 isolate, or the main context.
     exits before the next GC). With eager execution, the GC will be started
     right away to measure the memory.
     **Default:** `'default'`
-* Returns: {Promise} If the memory is successfully measured the promise will
+* Returns: {Promise} If the memory is successfully measured, the promise will
   resolve with an object containing information about the memory usage.
+  Otherwise it will be rejected with an `ERR_CONTEXT_NOT_INITIALIZED` error.
 
 The format of the object that the returned Promise may resolve with is
 specific to the V8 engine and may change from one version of V8 to the next.