doc: clarify Web Storage behavior

doc/api/cli.md

@@ -3385,6 +3385,15 @@ for MiB in 16 32 64 128; do
 done
 ```
 
+### --localstorage-file
+
+The --localstorage-file option specifies the file used for localStorage in Node.js.
+
+* This file can be accessed by multiple processes simultaneously, which
+  might require implementing file locking or other synchronization
+  mechanisms to ensure data integrity.
+* The storage quota for `localStorage` is 10MB per process.
+
 ### `--security-revert`
 
 ### `--stack-trace-limit=limit`

doc/api/globals.md

@@ -1199,6 +1199,20 @@ added: v18.0.0
 
 A browser-compatible implementation of [`WritableStreamDefaultWriter`][].
 
+## Web Storage API
+
+In Node.js, the localStorage and sessionStorage objects function differently compared to browsers or Deno:
+
+* Both `localStorage` and `sessionStorage` are scoped to the current process,
+  not individual users or server requests. This is crucial for applications
+  like server-side rendering.
+* `localStorage` uses the value of the `--localstorage-file` flag as its
+  origin. This file can be accessed simultaneously by multiple processes,
+  which may require implementing file locking or other synchronization
+  mechanisms to ensure data integrity.
+* The storage quota for both `localStorage` and `sessionStorage` is
+  10MB per process.
+
 [CommonJS module]: modules.md
 [CommonJS modules]: modules.md
 [ECMAScript module]: esm.md