doc: Add missing indexes/blockfilter/basic/ to doc/files.md
doc: Add missing indexes/blockfilter/basic/ to doc/files.md

Former-commit-id: 120b00f7263975eaaec52bb56ad38daa93f5f161
syscoin/syscoin2,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin2,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin2,syscoin/syscoin,syscoin/syscoin2,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin2,syscoin/syscoin2