doc: mark --heap-prof and related flags stable

PR-URL: #53343
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Ruy Adorno <ruy@vlt.sh>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>

doc/api/cli.md

@@ -1173,9 +1173,14 @@ To allow polyfills to be added,
 
 <!-- YAML
 added: v12.4.0
+changes:
+  - version:
+    - REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/53343
+    description: The `--heap-prof` flags are now stable.
 -->
 
-> Stability: 1 - Experimental
+> Stability: 2 - Stable
 
 Starts the V8 heap profiler on start up, and writes the heap profile to disk
 before exit.
@@ -1196,9 +1201,14 @@ Heap.20190409.202950.15293.0.001.heapprofile
 
 <!-- YAML
 added: v12.4.0
+changes:
+  - version:
+    - REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/53343
+    description: The `--heap-prof` flags are now stable.
 -->
 
-> Stability: 1 - Experimental
+> Stability: 2 - Stable
 
 Specify the directory where the heap profiles generated by `--heap-prof` will
 be placed.
@@ -1210,9 +1220,14 @@ The default value is controlled by the
 
 <!-- YAML
 added: v12.4.0
+changes:
+  - version:
+    - REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/53343
+    description: The `--heap-prof` flags are now stable.
 -->
 
-> Stability: 1 - Experimental
+> Stability: 2 - Stable
 
 Specify the average sampling interval in bytes for the heap profiles generated
 by `--heap-prof`. The default is 512 \* 1024 bytes.
@@ -1221,9 +1236,14 @@ by `--heap-prof`. The default is 512 \* 1024 bytes.
 
 <!-- YAML
 added: v12.4.0
+changes:
+  - version:
+    - REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/53343
+    description: The `--heap-prof` flags are now stable.
 -->
 
-> Stability: 1 - Experimental
+> Stability: 2 - Stable
 
 Specify the file name of the heap profile generated by `--heap-prof`.