fix builder spec link, add honest validator spec

Author: lightclient

README.md

@@ -7,7 +7,8 @@ built by external entities.
 
 In this repository:
 * [API specification][oas-spec]
-* [Additional definitions][spec]
+* [Builder specification][builder-spec]
+* [Honest validator specification][validator-spec]
 
 ### Why?
 
@@ -92,7 +93,8 @@ with real tag name from step 1.):
 
 [ci]: https://github.com/ethereum/builder-specs/workflows/CI/badge.svg
 [oas-spec]: https://ethereum.github.io/builder-specs/
-[spec]: specs/README.md
+[builder-spec]: specs/builder.md
+[validator-spec]: specs/validator.md
 [pbs]: https://ethresear.ch/t/proposer-block-builder-separation-friendly-fee-market-designs/9725
 [mev-boost-ethr]: https://ethresear.ch/t/mev-boost-merge-ready-flashbots-architecture/11177
 [mev-boost]: https://github.com/flashbots/mev-boost