Fix broken Markdown links (#8214)

- Remove pointless Makefile and package documentation.
- Fix broken links.

docs/introduction/what-is-tendermint.md

@@ -68,10 +68,10 @@ Tendermint is in essence similar software, but with two key differences:
 
 - It is Byzantine Fault Tolerant, meaning it can only tolerate up to a
   1/3 of failures, but those failures can include arbitrary behaviour -
-  including hacking and malicious attacks. 
-- It does not specify a particular application, like a fancy key-value 
-  store. Instead, it focuses on arbitrary state machine replication, 
-  so developers can build the application logic that's right for them, 
+  including hacking and malicious attacks.
+- It does not specify a particular application, like a fancy key-value
+  store. Instead, it focuses on arbitrary state machine replication,
+  so developers can build the application logic that's right for them,
   from key-value store to cryptocurrency to e-voting platform and beyond.
 
 ### Bitcoin, Ethereum, etc
@@ -104,12 +104,10 @@ to Tendermint, but is more opinionated about how the state is managed,
 and requires that all application behaviour runs in potentially many
 docker containers, modules it calls "chaincode". It uses an
 implementation of [PBFT](http://pmg.csail.mit.edu/papers/osdi99.pdf).
-from a team at IBM that is [augmented to handle potentially
-non-deterministic
-chaincode](https://www.zurich.ibm.com/~cca/papers/sieve.pdf) It is
-possible to implement this docker-based behaviour as a ABCI app in
-Tendermint, though extending Tendermint to handle non-determinism
-remains for future work.
+from a team at IBM that is augmented to handle potentially non-deterministic
+chaincode It is possible to implement this docker-based behaviour as a ABCI app
+in Tendermint, though extending Tendermint to handle non-determinism remains
+for future work.
 
 [Burrow](https://github.com/hyperledger/burrow) is an implementation of
 the Ethereum Virtual Machine and Ethereum transaction mechanics, with