Add reference to Soar Programmers Guide

Author: moschmdt

docs/explanations/SoarProgrammersGuide.md

@@ -0,0 +1,5 @@
+# Soar Programmer's Guide
+
+This is similar to the [design dogma](./DesignDogma.md), but written by Bob
+Marinier at Soartech and more up to date:
+[Soar Programmer's Guide](https://soartech.github.io/SoarProgrammersGuide/31654126.html).

docs/explanations/index.md

@@ -2,8 +2,9 @@
 
 This section provides some explanations about the decisions behind Soar.
 
-- [Basic Kernel Terminology](BasicKernelTerminology.md)
-- [Design Dogma](DesignDogma.md)
-- [Threads in SML](ThreadsInSML.md)
-- [Timers](Timers.md)
-- [Waterfall](Waterfall.md)
+-   [Basic Kernel Terminology](BasicKernelTerminology.md)
+-   [Design Dogma](DesignDogma.md)
+-   [Soar Programmers Guide](SoarProgrammersGuide.md)
+-   [Threads in SML](ThreadsInSML.md)
+-   [Timers](Timers.md)
+-   [Waterfall](Waterfall.md)

mkdocs.yml

@@ -90,6 +90,7 @@ nav:
       - explanations/index.md
       - Basic Kernel Terminology: explanations/BasicKernelTerminology.md
       - Design Dogma: explanations/DesignDogma.md
+      - Soar Programmer's Guide: explanations/SoarProgrammersGuide.md
       - Threads in SML: explanations/ThreadsInSML.md
       - Timers: explanations/Timers.md
       - Waterfall: explanations/Waterfall.md