docs: fix migration/docs for ICA controller middleware (cosmos#2737)

* update docs/migration with the change to middleware for ICA controller

* improve variable naming

* alignment

Co-authored-by: Carlos Rodriguez <crodveg@gmail.com>

docs/apps/interchain-accounts/integration.md

@@ -97,14 +97,15 @@ icaAuthModule := icaauth.NewAppModule(appCodec, app.ICAAuthKeeper)
 // ICA auth IBC Module
 icaAuthIBCModule := icaauth.NewIBCModule(app.ICAAuthKeeper)
 
-// Create host and controller IBC Modules as desired
-icaControllerIBCModule := icacontroller.NewIBCModule(app.ICAControllerKeeper, icaAuthIBCModule)
+// Create controller IBC application stack and host IBC module as desired
+icaControllerStack := icacontroller.NewIBCMiddleware(icaAuthIBCModule, app.ICAControllerKeeper)
 icaHostIBCModule := icahost.NewIBCModule(app.ICAHostKeeper)
 
 // Register host and authentication routes
-ibcRouter.AddRoute(icacontrollertypes.SubModuleName, icaControllerIBCModule).
-		AddRoute(icahosttypes.SubModuleName, icaHostIBCModule).
-		AddRoute(icaauthtypes.ModuleName, icaControllerIBCModule) // Note, the authentication module is routed to the top level of the middleware stack
+ibcRouter.
+    AddRoute(icacontrollertypes.SubModuleName, icaControllerStack).
+    AddRoute(icahosttypes.SubModuleName, icaHostIBCModule).
+    AddRoute(icaauthtypes.ModuleName, icaControllerStack) // Note, the authentication module is routed to the top level of the middleware stack
 
 ...
 
@@ -178,10 +179,11 @@ app.ICAAuthKeeper = icaauthkeeper.NewKeeper(appCodec, keys[icaauthtypes.StoreKey
 icaAuthModule := icaauth.NewAppModule(appCodec, app.ICAAuthKeeper)
 icaAuthIBCModule := icaauth.NewIBCModule(app.ICAAuthKeeper)
 
-// Create controller IBC Module
-icaControllerIBCModule := icacontroller.NewIBCModule(app.ICAControllerKeeper, icaAuthIBCModule)
+// Create controller IBC application stack
+icaControllerStack := icacontroller.NewIBCMiddleware(icaAuthIBCModule, app.ICAControllerKeeper)
 
 // Register controller and authentication routes
-ibcRouter.AddRoute(icacontrollertypes.SubModuleName, icaControllerIBCModule)
-ibcRouter.AddRoute(icaauthtypes.ModuleName, icaControllerIBCModule) // Note, the authentication module is routed to the top level of the middleware stack
+ibcRouter.
+    AddRoute(icacontrollertypes.SubModuleName, icaControllerStack).
+    AddRoute(icaauthtypes.ModuleName, icaControllerStack) // Note, the authentication module is routed to the top level of the middleware stack
 ```

docs/middleware/ics29-fee/integration.md

@@ -16,7 +16,7 @@ For Cosmos SDK chains this setup is done via the `app/app.go` file, where module
 
 ## Example integration of the Fee Middleware module
 
-```
+```go
 // app.go
 
 // Register the AppModule for the fee middleware module

docs/migrations/v3-to-v4.md

@@ -18,7 +18,18 @@ No genesis or in-place migrations required when upgrading from v1 or v2 of ibc-g
 
 ## Chains
 
-### Fee Middleware
+### ICS27 - Interchain Accounts
+
+The controller submodule implements now the 05-port `Middleware` interface instead of the 05-port `IBCModule` interface. Chains that integrate the controller submodule, need to create it with the `NewIBCMiddleware` constructor function. For example:
+
+```diff
+- icacontroller.NewIBCModule(app.ICAControllerKeeper, icaAuthIBCModule)
++ icacontroller.NewIBCMiddleware(icaAuthIBCModule, app.ICAControllerKeeper)
+```
+
+where `icaAuthIBCModule` is the Interchain Accounts authentication IBC Module.
+
+### ICS29 - Fee Middleware
 
 The Fee Middleware module, as the name suggests, plays the role of an IBC middleware and as such must be configured by chain developers to route and handle IBC messages correctly.