Fix typo in context and node docs (#8533)

* Update context.md

* fix typo in the node document

docs/core/context.md

@@ -13,7 +13,7 @@ The `context` is a data structure intended to be passed from function to functio
 
 ## Context Definition
 
-The SDK `Context` is a custom data structure that contains Go's stdlib [`context`](https://golang.org/pkg/context) as its base, and has many additional types within its definition that are specific to the Cosmos SDK. he `Context` is integral to transaction processing in that it allows modules to easily access their respective [store](./store.md#base-layer-kvstores) in the [`multistore`](./store.md#multistore) and retrieve transactional context such as the block header and gas meter.
+The SDK `Context` is a custom data structure that contains Go's stdlib [`context`](https://golang.org/pkg/context) as its base, and has many additional types within its definition that are specific to the Cosmos SDK. The `Context` is integral to transaction processing in that it allows modules to easily access their respective [store](./store.md#base-layer-kvstores) in the [`multistore`](./store.md#multistore) and retrieve transactional context such as the block header and gas meter.
 
 +++ https://github.com/cosmos/cosmos-sdk/blob/v0.40.0-rc3/types/context.go#L16-L39
 

docs/core/node.md

@@ -16,7 +16,7 @@ The full-node client of any SDK application is built by running a `main` functio
 
 In general, developers will implement the `main.go` function with the following structure:
 
-- First, an [`appCodec`](./encoding.md) is instanciated for the application.
+- First, an [`appCodec`](./encoding.md) is instantiated for the application.
 - Then, the `config` is retrieved and config parameters are set. This mainly involves setting the bech32 prefixes for [addresses and pubkeys](../basics/accounts.md#addresses-and-pubkeys).
   +++ https://github.com/cosmos/cosmos-sdk/blob/v0.40.0-rc3/types/config.go#L13-L24
 - Using [cobra](https://github.com/spf13/cobra), the root command of the full-node client is created. After that, all the custom commands of the application are added using the `AddCommand()` method of `rootCmd`.