Update to markdown links (#9384)

* first correction of markdown links

* Review updates

docs/tendermint-core/block-structure.md

@@ -11,6 +11,6 @@ nodes. This blockchain is accessible via various RPC endpoints, mainly
 `/blockchain?minHeight=_&maxHeight=_` to get a list of headers. But what
 exactly is stored in these blocks?
 
-The [specification](https://github.com/tendermint/spec/blob/8dd2ed4c6fe12459edeb9b783bdaaaeb590ec15c/spec/core/data_structures.md) contains a detailed description of each component - that's the best place to get started.
+The [specification](https://github.com/tendermint/tendermint/blob/main/spec/core/data_structures.md) contains a detailed description of each component - that's the best place to get started.
 
 To dig deeper, check out the [types package documentation](https://godoc.org/github.com/tendermint/tendermint/types).

docs/tendermint-core/how-to-read-logs.md

@@ -115,7 +115,7 @@ I[10-04|13:54:30.410] Recheck txs                                  module=mempoo
 Here is the list of modules you may encounter in Tendermint's log and a
 little overview what they do.
 
-- `abci-client` As mentioned in [Application Development Guide](../app-dev/app-development.md), Tendermint acts as an ABCI
+- `abci-client` As mentioned in [Application Development Guide](../app-dev/abci-cli.md), Tendermint acts as an ABCI
   client with respect to the application and maintains 3 connections:
   mempool, consensus and query. The code used by Tendermint Core can
   be found [here](https://github.com/tendermint/tendermint/blob/v0.34.x/abci/client).

docs/tendermint-core/running-in-production.md

@@ -101,7 +101,7 @@ for more information.
 Rate-limiting and authentication are another key aspects to help protect
 against DOS attacks. Validators are supposed to use external tools like
 [NGINX](https://www.nginx.com/blog/rate-limiting-nginx/) or
-[traefik](https://docs.traefik.io/middlewares/ratelimit/)
+[traefik](https://doc.traefik.io/traefik/middlewares/http/ratelimit/)
 to achieve the same things.
 
 ## Debugging Tendermint
@@ -332,7 +332,7 @@ We want `skip_timeout_commit=false` when there is economics on the line
 because proposers should wait to hear for more votes. But if you don't
 care about that and want the fastest consensus, you can skip it. It will
 be kept false by default for public deployments (e.g. [Cosmos
-Hub](https://cosmos.network/intro/hub)) while for enterprise
+Hub](https://hub.cosmos.network/)) while for enterprise
 applications, setting it to true is not a problem.
 
 - `consensus.peer_gossip_sleep_duration`

docs/tendermint-core/subscription.md

@@ -36,14 +36,14 @@ more information on query syntax and other options.
 
 You can also use tags, given you had included them into DeliverTx
 response, to query transaction results. See [Indexing
-transactions](./indexing-transactions.md) for details.
+transactions](../app-dev/indexing-transactions.md) for details.
 
 ## ValidatorSetUpdates
 
 When validator set changes, ValidatorSetUpdates event is published. The
 event carries a list of pubkey/power pairs. The list is the same
 Tendermint receives from ABCI application (see [EndBlock
-section](https://github.com/tendermint/tendermint/blob/main/spec/abci/abci.md#endblock) in
+section](https://github.com/tendermint/tendermint/blob/main/spec/abci/abci++_methods.md#endblock) in
 the ABCI spec).
 
 Response:

docs/tendermint-core/using-tendermint.md

@@ -555,7 +555,7 @@ failing, you need at least four validator nodes (e.g., 2/3).
 
 Updating validators in a live network is supported but must be
 explicitly programmed by the application developer. See the [application
-developers guide](../app-dev/app-development.md) for more details.
+developers guide](../app-dev/abci-cli.md) for more details.
 
 ### Local Network
 

docs/tendermint-core/validators.md

@@ -97,7 +97,7 @@ More Information can be found at these links:
 
 ### Validator keys
 
-Protecting a validator's consensus key is the most important factor to take in when designing your setup. The key that a validator is given upon creation of the node is called a consensus key, it has to be online at all times in order to vote on blocks. It is **not recommended** to merely hold your private key in the default json file (`priv_validator_key.json`). Fortunately, the [Interchain Foundation](https://interchain.io/) has worked with a team to build a key management server for validators. You can find documentation on how to use it [here](https://github.com/iqlusioninc/tmkms), it is used extensively in production. You are not limited to using this tool, there are also [HSMs](https://safenet.gemalto.com/data-encryption/hardware-security-modules-hsms/), there is not a recommended HSM.
+Protecting a validator's consensus key is the most important factor to take in when designing your setup. The key that a validator is given upon creation of the node is called a consensus key, it has to be online at all times in order to vote on blocks. It is **not recommended** to merely hold your private key in the default json file (`priv_validator_key.json`). Fortunately, the [Interchain Foundation](https://interchain.io) has worked with a team to build a key management server for validators. You can find documentation on how to use it [here](https://github.com/iqlusioninc/tmkms), it is used extensively in production. You are not limited to using this tool, there are also [HSMs](https://safenet.gemalto.com/data-encryption/hardware-security-modules-hsms/), there is not a recommended HSM.
 
 Currently Tendermint uses [Ed25519](https://ed25519.cr.yp.to/) keys which are widely supported across the security sector and HSMs.