Standalone: Clarified translated installations

I did install standalone using option 1 (using the release tarball) and then installed the Internationalization files. However the option groups and location types wheren't translated after installing standalone.

I figured out that when I copied the l10n folder to private/l10n then the translation was ok.

docs/standalone/index.md

@@ -104,7 +104,7 @@ The default CiviCRM language is US English (`en_US`). You can select a different
 
 Alternatively, if you need the web installer in another language you can manually download all the translation files now.
 
-Head to https://civicrm.org/download and choose "Internationalisation files" from the Download dropdown, then extract these into your `core` directory. The extracted files should end up in `core/l10n` and `core/sql`.
+Head to https://civicrm.org/download and choose "Internationalisation files" from the Download dropdown, then copy the `l10n` directory from the download into the `private` directory of your site (so you should end up with folders like `private/l10n/es_ES`).
 
 
 ## Step 5. Configure MySQL {:#mysql}