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

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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

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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)

x/authz/spec/02_state.md

@@ -12,7 +12,7 @@ Grants are identified by combining granter address (the address bytes of the gra
 
 The grant object encapsulates an `Authorization` type and an expiration timestamp:
 
-+++ https://github.com/cosmos/cosmos-sdk/blob/v0.46.0-beta2/proto/cosmos/authz/v1beta1/authz.proto#L22-L30
++++ https://github.com/cosmos/cosmos-sdk/blob/v0.46.0-rc1/proto/cosmos/authz/v1beta1/authz.proto#L22-L30
 
 ## GrantQueue
 
@@ -20,4 +20,4 @@ We are maintaining a queue for authz pruning, whenever a grant created an item w
 
 * GrantQueue: `0x02 | granter_address_len (1 byte) | granter_address_bytes | grantee_address_len (1 byte) | grantee_address_bytes | expiration_bytes -> ProtocalBuffer([]string{msgTypeUrls})`
 
-+++ https://github.com/cosmos/cosmos-sdk/blob/v0.46.0-beta2/x/authz/keeper/keys.go#L86-L102
++++ https://github.com/cosmos/cosmos-sdk/blob/v0.46.0-rc1/x/authz/keeper/keys.go#L78-L93