specs: Full table of contents (#2860)

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

specs/README.md

@@ -6,11 +6,19 @@ that maintains 1:1 compatibility with Ethereum.
 
 ## Specification Contents
 
-- [Glossary](glossary.md)
+- [Introduction](introduction.md)
+- [Overview](overview.md)
 - [Deposits](deposits.md)
+- [Withdrawals](withdrawals.md)
 - [Execution Engine](exec-engine.md)
 - [L2 Output Root Proposals](proposals.md)
 - [Rollup Node](rollup-node.md)
+- [Rollup Node P2p](rollup-node-p2p.md)
+- [Guaranteed Gas Market](guaranteed-gas-market.md)
+- [Messengers](messengers.md)
+- [Bridges](bridges.md)
+- [Predeploys](predeploys.md)
+- [Glossary](glossary.md)
 
 ## Design Goals