Update README.md

[mtefagh]

All Submissions:

• [x] Have you followed the guidelines in our Contributing documentation?
• [x] Have you verified that there aren't any other open Pull Requests for the same update/change?
• [x] Does the Pull Request pass all tests?

Description

Updated the README file with a few minor changes

Checklist

/ Keep from below the appropriate checklist for your Pull Request and remove the others /

New Ledger Support Submissions:

• What mapping information did you add for the new ledger?
  • [ ] identifiers
  • [ ] addresses
  • [ ] clusters
  • [ ] legal links
• Did you create a new parser?
  • [ ] If yes, did you create a unit test for the new parser?
  • [ ] If no, which parser did you reuse?
  • [ ] DefaultParser
  • [ ] DummyParser
  • [ ] EthereumParser
• Did you create a new mapping?
  • [ ] If yes, did you create a unit test for the new mapping?
  • [ ] If no, which mapping did you reuse? / mapping name /
  • [ ] DefaultMapping
  • [ ] DummyMapping
  • [ ] EthereumMapping
  • [ ] CardanoMapping
  • [ ] TezosMapping
• [ ] Did you enable the parser for the new ledger in consensus_decentralization/parse.py?
• [ ] Did you enable the mapping for the new ledger in consensus_decentralization/map.py?
• [ ] Did you document support for the new ledger as described in our Contributing documentation?

Update Mapping Support Information Submissions:

• For which ledger do you update the mapping information?
  • [ ] / ledger name /
• What mapping information do you update?
  • [ ] identifiers
  • [ ] addresses
  • [ ] clusters
  • [ ] legal links
• [ ] Did you update the tests (if needed)?

New Metric Support Submissions:

• [ ] Did you put the metric's script under consensus_decentralization/metrics?
• [ ] Did you name the metric's main function of the script compute_{metric name}?
• [ ] Did you import the metric's main function to consensus_decentralization/analyze.py?
• [ ] Did you add the new metric (and possible parameter values) to config.yaml?
• [ ] Did you write unit tests for the new metric?
• [ ] Did you document the new metric in the documentation pages?