Documentation update: Deploy Key policy "enabled"/"disabled" (#648)

## 📝 Description
#633

## ✅ Checklist
- [x] I have tested this change
- [x] This change requires documentation update

---------

Co-authored-by: Diego Guerra <[email protected]>
Co-authored-by: Tomas Fernandez <[email protected]>

Author: 3 people

docs/docs/using-semaphore/connect-github.md

@@ -120,6 +120,38 @@ A deploy key can be invalidated if:
 
 :::
 
+### Verify deploy key settings on GitHub {#deploy-key-github}
+
+GitHub recently changed the default setting for Deploy keys, which may now be set to Disabled for new organizations. When this setting is disabled, Semaphore cannot create or connect projects from GitHub repositories.
+
+If you encounter issues connecting Semaphore to your GitHub repository (for example, projects failing to create or the connection breaking), please verify your deploy key configuration, depending on the type of GitHub account:
+
+#### GitHub organization accounts:
+
+1. Go to your organization’s settings page on GitHub: https://github.com/organizations/ORGANIZATION_NAME/settings/deploy_keys
+1. Under **Security → Deploy keys**, check the **Default policy** setting.
+1. If the default option is **Disabled**, change it to **Enabled**.
+
+    <img width="626" height="234" alt="Image" src="https://github.com/user-attachments/assets/ca603af3-cbbc-47b2-b566-f1912704b8fe" />
+
+1. Once updated, retry creating or reconnecting your project on Semaphore.
+
+#### GitHub Enterprise Accounts:**
+
+For GitHub Enterprise Cloud users, deploy key policies are controlled at the enterprise level. A user with Admin permissions must enable deploy keys.
+
+1. Log in to your GitHub Enterprise Cloud account as an admin.
+
+1. Follow the instructions in GitHub’s documentation: [Enforcing a policy for deploy keys in your enterprise](https://docs.github.com/en/enterprise-cloud@latest/admin/enforcing-policies/enforcing-policies-for-your-enterprise/enforcing-repository-management-policies-in-your-enterprise#enforcing-a-policy-for-deploy-keys)
+
+    - In the top-right corner of GitHub, click your profile picture.
+    - Click on **Your enterprise/Your enterprises** and select your organization.
+    - Click on **Policies > Member privileges**.
+    - Under **Deploy keys**, review the information about changing the setting, select a policy, and save.
+
+1. Once updated, retry creating or reconnecting your project on Semaphore.
+
+
 ### Verify webhook health {#webhook}
 
 Semaphore uses a webhook to detect changes in your repository. When the webhook is broken, Semaphore can't trigger new workflows.