update migration guide url

Author: ryanwaits

content/docs/stacks/stacks.js/packages/common.mdx

@@ -16,7 +16,7 @@ import { Callout } from "@/components/callout";
 
 <Callout type="info">
 This reference refers to the `7.x.x` release of Stacks.js—it's the recommended version to use, but not needed for the Stacks Nakamoto release.
-Read the [migration guide](https://github.com/hirosystems/stacks.js/blob/next/.github/MIGRATION.md#stacksjs-5xx--7xx) to learn how to update to the latest version.
+Read the [migration guide](https://github.com/hirosystems/stacks.js/blob/main/.github/MIGRATION.md#stacksjs-5xx--7xx) to learn how to update to the latest version.
 </Callout>
 
 The `@stacks/common` package contains common utilities for working with Stacks.

content/docs/stacks/stacks.js/packages/network.mdx

@@ -16,7 +16,7 @@ import { Callout } from "@/components/callout";
 
 <Callout type="info">
 This reference refers to the `7.x.x` release of Stacks.js—it's the recommended version to use, but not needed for the Stacks Nakamoto release.
-Read the [migration guide](https://github.com/hirosystems/stacks.js/blob/next/.github/MIGRATION.md#stacksjs-5xx--7xx) to learn how to update to the latest version.
+Read the [migration guide](https://github.com/hirosystems/stacks.js/blob/main/.github/MIGRATION.md#stacksjs-5xx--7xx) to learn how to update to the latest version.
 </Callout>
 
 The `@stacks/network` package contains default network configurations for Stacks.