cli: mark --heapsnapshot-near-heap-limit as stable

This has not changed in the past 5 years and has been passing the tests
for 5 years. Mark it as stable.

PR-URL: https://github.com/nodejs/node/pull/60956
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

doc/api/cli.md

@@ -1512,10 +1512,13 @@ Specify the file name of the heap profile generated by `--heap-prof`.
 added:
   - v15.1.0
   - v14.18.0
+changes:
+  - version:
+    - REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/60956
+    description: The flag is no longer experimental.
 -->
 
-> Stability: 1 - Experimental
-
 Writes a V8 heap snapshot to disk when the V8 heap usage is approaching the
 heap limit. `count` should be a non-negative integer (in which case
 Node.js will write no more than `max_count` snapshots to disk).