fix: expose update --no-save in CLI help (#12091)

The update command already honors --no-save and the docs already
mention it, but the flag was missing from the update command
metadata.

Add the option entry so pnpm update --help shows it and the CLI
surface matches the documented behavior.

.changeset/fix-update-no-save-option.md

@@ -0,0 +1,6 @@
+---
+"@pnpm/installing.commands": patch
+"pnpm": patch
+---
+
+Register the `pnpm update --no-save` flag in the CLI help and option parser.

installing/commands/src/update/index.ts

@@ -151,6 +151,10 @@ dependencies is not found inside the workspace',
             name: '--interactive',
             shortAlias: '-i',
           },
+          {
+            description: 'Don\'t update the ranges in package.json.',
+            name: '--no-save',
+          },
           OPTIONS.globalDir,
           ...UNIVERSAL_OPTIONS,
         ],