Update README.rst

[ci skip]

Merge pull request #183 from nelsontodd/update-submodule

Point external/range-v3 submodule to relevant extant commit

Update to new AMI

Fix typo in last commit

Merge pull request #58 from citp/SwitchToRocksDB

Update BlockSci master to v0.4

BlockSci Version 0.3 Release featuring segwit support and many bug fixes

Merge pull request #16 from abirke/fix-mapreduce

Fix MapReduce