docs: update "adding params"

docusaurus/docs/develop/developer_guide/adding_params.md

@@ -43,6 +43,43 @@ https://github.com/ignite/cli/issues/3684#issuecomment-2299796210
 
 ## Step-by-Step Instructions
 
+### 0. If the Module Doesn't Already Support a `MsgUpdateParam` Message
+
+In order to support **individual parameter updates**, the module MUST have a `MsgUpdateParam` message.
+If the module doesn't already support this message, it will need to be added.
+
+### 0.1 Scaffold the `MsgUpdateParam` Message
+
+```bash
+ignite scaffold message update-param --module <module-name> --signer authority name as_type --response params
+```
+
+### 0.2 Update the `MsgUpdateParam` Message Fields
+
+Update the `MsgUpdateParam` message fields in the module's `tx.proto` file to include the following comments and protobuf options:
+
+```diff
++// MsgUpdateParam is the Msg/UpdateParam request type to update a single param.
+ message MsgUpdateParam {
+   option (cosmos.msg.v1.signer) = "authority";
+-  string authority = 1;
++
++  // authority is the address that controls the module (defaults to x/gov unless overwritten).
++  string authority = 1  [(cosmos_proto.scalar) = "cosmos.AddressString"];
++
+   string name      = 2;
+-  string asType    = 3;
++  oneof as_type {
++    // Add `as_<type>` fields for each type in this module's Params type; e.g.:
++    // int64 as_int64 = 3 [(gogoproto.jsontag) = "as_int64"];
++    // bytes as_bytes = 4 [(gogoproto.jsontag) = "as_bytes"];
++    // cosmos.base.v1beta1.Coin as_coin = 5 [(gogoproto.jsontag) = "as_coin"];
++  }
+ }
+
+ message MsgUpdateParamResponse {
+```
+
 ### 1. Define the Parameter in the Protocol Buffers File
 
 Open the appropriate `.proto` file for your module (e.g., `params.proto`) and define the new parameter.
@@ -56,9 +93,57 @@ message Params {
 }
 ```
 
-### 2 Update the Parameter Integration Tests
+### 2 Update the Parameter Integration Tests 
+
+Integration tests which cover parameter updates utilize the `ModuleParamConfig`s defined in [`testutil/integration/params/param_configs.go`](https://github.com/pokt-network/poktroll/blob/main/testutil/integration/suites/param_configs.go) to dynamically (i.e. using reflection) construct and send parameter update messages in a test environment.
+When adding parameters to a module, it is necessary to update that module's `ModuleParamConfig` to include the new parameter, othwerwise it will not be covered by the integration test suite.
+
+### 2.1 If the Module Didn't Previously Support a `MsgUpdateParam` Message
+
+  Add `MsgUpdateParam` & `MsgUpdateParamResponse` to the module's `ModuleParamConfig#ParamsMsg`:
+
+```diff
+SomeModuleParamConfig = ModuleParamConfig{
+  ParamsMsgs: ModuleParamsMessages{
+    MsgUpdateParams:         gatewaytypes.MsgUpdateParams{},
+    MsgUpdateParamsResponse: gatewaytypes.MsgUpdateParamsResponse{},
++   MsgUpdateParam:          gatewaytypes.MsgUpdateParam{},
++   MsgUpdateParamResponse:  gatewaytypes.MsgUpdateParamResponse{},
+    QueryParamsRequest:      gatewaytypes.QueryParamsRequest{},
+    QueryParamsResponse:     gatewaytypes.QueryParamsResponse{},
+  },
+  ...
+}
+```
+
+### 2.2 Add a valid param
 
-// TODO_DOCUMENT(@bryanchriswhite, #826)
+Update `ModuleParamConfig#ValidParams` to include a valid and non-default value for the new parameter.
+
+```diff
+SomeModuleParamConfig = ModuleParamConfig{
+    ...
+    ValidParams: gatewaytypes.Params{
++       MinStake: &ValidActorMinStake,
+    },
+    ...
+}
+```
+
+### 2.3 Check for `as_<type>` on `MsgUpdateParam`
+
+Ensure an `as_<type>` field exists on `MsgUpdateParam` corresponding to the type of the new parameter.
+Below is an example of adding an `int64` type parameter to a new `MsgUpdateParam` message:
+
+```diff
+ message MsgUpdateParam {
+   ...
+   oneof as_type {
+-    // Add `as_<type>` fields for each type in this module's Params type; e.g.:
++    int64 as_int64 = 3 [(gogoproto.jsontag) = "as_int64"];
+   }
+ }
+```
 
 ### 3. Update the Default Parameter Values