Add TODO list for circuit

circuit/README.md

@@ -0,0 +1,16 @@
+# Brainfuck collection
+
+## logisim circuit
+
+### TODO
+
+- Expand return address register to stack
+- Implement memory as in- and output for more complex in- and output programs
+
+## brainfuck bfpu assembler
+
+
+## brainfuck bfpu (FPGA)
+
+
+## brainfuck bfpu (TinyTapeout)