ad-swiot1l-sl: Add production testing guide

[plescaevelyn]

Add comprehensive production testing documentation for the AD-SWIOT1L-SL software-configurable I/O platform. This guide is intended for manufacturing and QA teams to verify board functionality.

Content includes:

• Test duration estimates (30 min setup, 5 min per system)
• Required hardware list (Raspberry Pi 4, DAPLink, T1L cables, etc.)
• DUTs: AD-SWIOT1L-SL, AD-T1LUSB2.0-EBZ, T1L cable
• Step-by-step setup instructions with images
• WiFi setup on Raspberry Pi (optional)
• Hardware setup and DUT connections

Test process documentation:

• 1. Memory/MAXQ1065 Tests (firmware, UART, RAM, Flash, LED checks)
• 2. AD74413R/MAX14906 Tests (with loopback terminal block)
• 3. Program Final Firmware (T1L power, switch position)
• Pass/fail criteria and retry guidelines

Type

• Documentation
• Bug fix
• New feature
• Continuous integration

Checklist

• I have performed a self-review of changes
• I have followed the guidelines:
  • https://analogdevicesinc.github.io/documentation/contributing/docs_guidelines.html
  • https://analogdevicesinc.github.io/doctools/docs_guidelines/index.html
  • https://analogdevicesinc.github.io/documentation/contributing/creating_new_pages.html#documentation-structure
• I have used the appropriate roles and directives:
  • https://analogdevicesinc.github.io/doctools/docs_guidelines/roles.html
  • https://analogdevicesinc.github.io/doctools/docs_guidelines/directives.html
• I ensured that binary data was committed to git lfs:
  • https://analogdevicesinc.github.io/documentation/contributing/creating_new_pages.html#adding-images-and-other-binary-files
• I have built the pages I edited or created, using either make html or adoc serve:
  • https://analogdevicesinc.github.io/doctools/cli.html#serve
• I have signed-off my commits and believe my contribution improves the repository.