Enable url redirect (#374)

* Enable url redirect

Author: montyly

Diff for: README.md

@@ -29,7 +29,7 @@ Brought to you by [Trail of Bits](https://www.trailofbits.com/), this repository
   - [Solana](./not-so-smart-contracts/solana)
 - [Program Analysis](./program-analysis): Using automated tools to secure contracts
   - [Echidna](./program-analysis/echidna): A fuzzer that checks your contract's properties
-  - [Medusa](./program-analysis/medusa): A next-gen fuzzer that checks your contract's properties
+  - [Medusa](./program-analysis/medusa/docs/src): A next-gen fuzzer that checks your contract's properties
   - [Slither](./program-analysis/slither): A static analyzer with both CLI and scriptable interfaces
   - [Manticore](./program-analysis/manticore): A symbolic execution engine that proves the correctness of properties
   - For each tool, this training material provides:

Diff for: book.toml

@@ -20,3 +20,8 @@ mathjax-support = true
 [output.html.fold]
 enable = true
 level = 1
+
+[output.html.redirect]
+"medusa/index.html" = "../program-analysis/medusa/docs/src"
+"slither/index.html" = "../program-analysis/slither"
+"echidna/index.html" = "../program-analysis/echidna"