Typo in PDK documentaion

In [Device Details](https://skywater-pdk.readthedocs.io/en/latest/rules/device-details.html), There is, assumed to be, a typo in a table for SONOS device. It says -38 V for Vs voltage during program. It is expected to be -3.8 V. Also schematic figure for 2-T SONOS memory cell can not be displayed.

Start with the Device Details page linked in the issue and inspect the SONOS device table and the 2-T SONOS memory cell schematic figure. Verify the Vs value against the documented expectation and investigate why the figure cannot be displayed. Done means the typo is corrected and the schematic renders correctly in the documentation.

Written by the indexing model from the issue text.