Write some amount of documentation

docs/lofi.md

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+# Lo-fi Effects
+
+Add grit, warmth, and character with bit crushing, folding, and distortion.
+
+## Bit Crush
+
+Reduce bit depth for digital artifacts:
+
+```forth
+"drum" s 8 crush .   ( 8-bit crush )
+"drum" s 4 crush .   ( heavy 4-bit crush )
+```
+
+## Wave Folding
+
+Fold the waveform back on itself for complex harmonics:
+
+```forth
+"sine" s 2 fold .    ( moderate folding )
+"sine" s 4 fold .    ( aggressive folding )
+```
+
+## Wave Wrap
+
+Wrap the waveform for a different flavor of distortion:
+
+```forth
+"bass" s 0.5 wrap .
+```
+
+## Distortion
+
+Classic overdrive/distortion:
+
+```forth
+"guitar" s 0.5 distort .     ( distortion amount )
+"guitar" s 0.8 distortvol .  ( output volume )
+```
+
+## Combining Effects
+
+```forth
+"drum" s
+  12 crush
+  1.5 fold
+  0.3 distort
+.
+```
+
+## Words
+
+| Word | Stack | Description |
+|------|-------|-------------|
+| `crush` | (f --) | Set bit crush depth |
+| `fold` | (f --) | Set wave fold amount |
+| `wrap` | (f --) | Set wave wrap amount |
+| `distort` | (f --) | Set distortion amount |
+| `distortvol` | (f --) | Set distortion output volume |