Fix broken custom networks link in installation docs

- Update relative path from '../../core/custom-networks' to 'custom-networks' in snippet files
- Fix affects React, Vue, Next.js, and JavaScript wagmi implementation snippets
- Links now work correctly when snippets are imported into installation documentation
- Both installation.mdx and custom-networks.mdx are in same directory (/appkit/react/core/)

Co-Authored-By: enes@reown.com <enes@reown.com>

Author: devin-ai-integration[bot]

snippets/appkit/javascript/wagmi/about/implementation.mdx

@@ -59,5 +59,5 @@ import { mainnet, arbitrum, base, scroll, polygon } from '@reown/appkit/networks
 ```
 
 <Note>
-Looking to add a custom network? Check out the [custom networks](../../core/custom-networks) section.
+Looking to add a custom network? Check out the [custom networks](custom-networks) section.
 </Note>

snippets/appkit/next/wagmi/about/implementation.mdx

@@ -45,7 +45,7 @@ import { mainnet, arbitrum, base, scroll, polygon } from '@reown/appkit/networks
 ```
 
 <Note>
-Looking to add a custom network? Check out the [custom networks](../../core/custom-networks) section.
+Looking to add a custom network? Check out the [custom networks](custom-networks) section.
 </Note>
 
 ## SSR and Hydration

snippets/appkit/react/wagmi/about/implementation.mdx

@@ -66,5 +66,5 @@ import { mainnet, arbitrum, base, scroll, polygon } from '@reown/appkit/networks
 ```
 
 <Note>
-Looking to add a custom network? Check out the [custom networks](../../core/custom-networks) section.
+Looking to add a custom network? Check out the [custom networks](custom-networks) section.
 </Note>

snippets/appkit/vue/wagmi/about/implementation.mdx

@@ -59,5 +59,5 @@ import { mainnet, arbitrum, base, scroll, polygon } from '@reown/appkit/networks
 ```
 
 <Note>
-Looking to add a custom network? Check out the [custom networks](../../core/custom-networks) section.
+Looking to add a custom network? Check out the [custom networks](custom-networks) section.
 </Note>