doc: join parts of disrupt section in cli.md

Also eliminate some redundancy.

PR-URL: #30038
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

doc/api/cli.md

@@ -244,7 +244,8 @@ added: v12.0.0
 -->
 
 Enables a signal handler that causes the Node.js process to write a heap dump
-when the specified signal is received.
+when the specified signal is received. `signal` must be a valid signal name.
+Disabled by default.
 
 ```console
 $ node --heapsnapshot-signal=SIGUSR2 index.js &
@@ -307,9 +308,6 @@ added: v12.4.0
 
 Specify the file name of the heap profile generated by `--heap-prof`.
 
-Generates a heap snapshot each time the process receives the specified signal.
-`signal` must be a valid signal name. Disabled by default.
-
 ### `--http-parser=library`
 <!-- YAML
 added: v11.4.0