There are several different ways that you can send additional information to your crew, such as staff handbooks, sitemaps, or other info.
Per Pass Type
If you always want to send certain attachments along with a specific pass type, you can do so. Here's the help article link.
Per Area/Sub-area
If you wish to send an attachment to everyone with a section, you can also do this. Within your section go to Settings > Uploads and upload a file.
You then have two options.
A) Tick 'include in all emails' this will automatically attach the file to any email sent within this section.
B) Don't tick it and leave it as optional. You will see this option whenever you see an email template preview:
Share documents via link
You could also include document links in email templates, by uploading a document and then including a link to it in your templates.