docs: add .env symlink setup instructions for apps/web (#287)

Co-authored-by: Claude <noreply@anthropic.com>

Author: nt-mino

CONTRIBUTION.md

@@ -55,6 +55,14 @@ openssl rand -base64 32
 
 - Add this to `.env` as `NEXTAUTH_SECRET`.
 
+- Create symlink for Next.js:
+
+```bash
+ln -s ../../.env apps/web/.env
+```
+
+> Next.js requires the `.env` file in its directory. This symlink ensures both root and `apps/web` can access the same environment variables.
+
 ### 4. GitHub OAuth (Optional for Dev)
 
 Set up a GitHub OAuth App:

apps/docs/get-started/local.mdx

@@ -98,6 +98,14 @@ pnpm install
 
 ```bash
 openssl rand -base64 32
+```
+
+  </Step>
+  <Step title="Create symlink for Next.js">
+  Create a symlink so that Next.js can access the root `.env` file:
+
+```bash
+ln -s ../../.env apps/web/.env
 ```
 
   </Step>