Fix docs navigation

(cherry picked from commit 3fe65ef4673f118da396c2d1027ec01116614aff)

scripts/prepare-docs.sh

@@ -18,4 +18,6 @@ solidity-docgen \
   --helpers ./docs/helpers.js \
   --solc-module ./scripts/prepare-docs-solc.js
 
+rm -f "$OUTDIR"/token/*/presets.md
+
 node scripts/gen-nav.js "$OUTDIR" > "$OUTDIR/../nav.adoc"