docs: revert middleware documentation and adds posthandler documentation (#11988)

## Description

ref: #11955

- [x] Reverts the documentation updates about middlewares (#11918, #11445 and part of #11860).
- [x] Adds explanation about post-handlers
---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [x] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [x] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#pr-targeting))
- [x] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/main/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [x] reviewed "Files changed" and left comments if necessary
- [x] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

docs/intro/sdk-app-architecture.md

@@ -84,8 +84,8 @@ Note that **Tendermint only handles transaction bytes**. It has no knowledge of
 
 Here are the most important messages of the ABCI:
 
-* `CheckTx`: When a transaction is received by Tendermint Core, it is passed to the application to check if a few basic requirements are met. `CheckTx` is used to protect the mempool of full-nodes against spam transactions. The [middlewares](../basics/gas-fees.md#middleware) `CheckTx` are used to execute a series of validation steps such as checking for sufficient fees and validating the signatures. If the checks are valid, the transaction is added to the [mempool](https://docs.tendermint.com/v0.34/tendermint-core/mempool.html#mempool) and relayed to peer nodes. Note that transactions are not processed (i.e. no modification of the state occurs) with `CheckTx` since they have not been included in a block yet.
-* `DeliverTx`: When a [valid block](https://docs.tendermint.com/v0.34/spec/blockchain/blockchain.html#validation) is received by Tendermint Core, each transaction in the block is passed to the application via `DeliverTx` in order to be processed. It is during this stage that the state transitions occur. The `middleware` executes its defined `DeliverTx`, along with the actual [`Msg` service](../building-modules/msg-services.md) RPC for each message in the transaction.
+* `CheckTx`: When a transaction is received by Tendermint Core, it is passed to the application to check if a few basic requirements are met. `CheckTx` is used to protect the mempool of full-nodes against spam transactions. . A special handler called the [`AnteHandler`](../basics/gas-fees.md#antehandler) is used to execute a series of validation steps such as checking for sufficient fees and validating the signatures. If the checks are valid, the transaction is added to the [mempool](https://docs.tendermint.com/v0.34/tendermint-core/mempool.html#mempool) and relayed to peer nodes. Note that transactions are not processed (i.e. no modification of the state occurs) with `CheckTx` since they have not been included in a block yet.
+* `DeliverTx`: When a [valid block](https://docs.tendermint.com/v0.34/spec/blockchain/blockchain.html#validation) is received by Tendermint Core, each transaction in the block is passed to the application via `DeliverTx` in order to be processed. It is during this stage that the state transitions occur. The `AnteHandler` executes again, along with the actual [`Msg` service](../building-modules/msg-services.md) RPC for each message in the transaction.
 * `BeginBlock`/`EndBlock`: These messages are executed at the beginning and the end of each block, whether the block contains transactions or not. It is useful to trigger automatic execution of logic. Proceed with caution though, as computationally expensive loops could slow down your blockchain, or even freeze it if the loop is infinite.
 
 Find a more detailed view of the ABCI methods from the [Tendermint docs](https://docs.tendermint.com/v0.35/introduction/what-is-tendermint.html#abci-overview).

docs/intro/why-app-specific.md

@@ -66,7 +66,7 @@ decentralized applications built with Smart Contracts are inherently capped in p
 
 Security is hard to quantify, and greatly varies from platform to platform. That said here are some important benefits an application-specific blockchain can bring in terms of security:
 
-* Developers can choose proven programming languages like Golang when building their application-specific blockchains, as opposed to smart contract programming languages that are often more immature.
+* Developers can choose proven programming languages like Go when building their application-specific blockchains, as opposed to smart contract programming languages that are often more immature.
 * Developers are not constrained by the cryptographic functions made available by the underlying virtual-machines. They can use their own custom cryptography, and rely on well-audited crypto libraries.
 * Developers do not have to worry about potential bugs or exploitable mechanisms in the underlying virtual-machine, making it easier to reason about the security of the application.