docs: moving code examples

Code now resides in `docs/source/code_examples`.
`CHAPTER_Prog` -> `stubnets`
`APPNOTE_011_Design_Investigation` -> `selections` and `show`
`resources/PRESENTATION_Intro` -> `intro`
`resources/PRESENTATION_ExSyn` -> `synth_flow`
`resources/PRESENTATION_ExAdv` -> `techmap`,  `macc`, and `selections`
`resources/PRESENTATION_ExOth` -> `scrambler` and `axis`

Note that generated images are not yet configured to build from the new code locations.

docs/source/code_examples/techmap/Makefile

@@ -0,0 +1,21 @@
+PROGRAM_PREFIX :=
+
+YOSYS ?= ../../../$(PROGRAM_PREFIX)yosys
+
+all: red_or3x1.dot sym_mul.dot mymul.dot mulshift.dot addshift.dot
+
+red_or3x1.dot: red_or3x1_*
+	$(YOSYS) red_or3x1_test.ys
+
+sym_mul.dot: sym_mul_*
+	$(YOSYS) sym_mul_test.ys
+
+mymul.dot: mymul_*
+	$(YOSYS) mymul_test.ys
+
+mulshift.dot: mulshift_*
+	$(YOSYS) mulshift_test.ys
+
+addshift.dot: addshift_*
+	$(YOSYS) addshift_test.ys
+