Add documentation for all PDF tools

docs/tools/add-attachments.md

@@ -0,0 +1,49 @@
+---
+title: Add Attachments
+description: Embed files of any type into a PDF at the document level or attached to specific pages.
+---
+
+# Add Attachments
+
+Embed one or more files directly inside a PDF document. Attachments can be added at the document level (visible in any PDF reader's attachment panel) or bound to specific pages.
+
+## How It Works
+
+1. Upload the PDF you want to attach files to.
+2. Use the attachment drop zone to select the files you want to embed (any file type).
+3. Choose the attachment level: **Document** (default) or **Page**.
+4. If you choose Page level, enter a page range (e.g., `1-3` or `5`).
+5. Click the process button. The modified PDF downloads with your files embedded.
+
+## Features
+
+- Attach any file type -- images, spreadsheets, archives, executables, anything
+- Document-level or page-level attachment placement
+- Multiple files can be attached in a single operation
+- Displays file names and sizes for all selected attachments
+- Output preserves the original PDF content with embedded files added
+
+## Options
+
+| Option             | Description                                                                |
+| ------------------ | -------------------------------------------------------------------------- |
+| **Document level** | Attaches files to the PDF as a whole, accessible from the attachment panel |
+| **Page level**     | Attaches files to specific pages, specified by a page range input          |
+
+## Use Cases
+
+- Bundling source data (Excel files, CSVs) with a PDF report
+- Attaching original image files to a photography portfolio PDF
+- Embedding supporting documents inside a contract or proposal
+- Adding supplementary materials to specific pages of a training manual
+
+## Tips
+
+- Document-level attachments are the most widely supported across PDF readers. Page-level attachments may not be visible in all viewers.
+- There is no file size limit for attachments, but very large embedded files will increase the PDF size proportionally.
+
+## Related Tools
+
+- [Extract Attachments](./extract-attachments)
+- [Edit Attachments](./edit-attachments)
+- [Merge PDF](./merge-pdf)