Add support for service variables to Railway integration, add docs for Railway

docs/integrations/cloud/railway.mdx

@@ -0,0 +1,54 @@
+---
+title: "Railway"
+description: "How to automatically sync secrets from Infisical into your Railway projects and services"
+---
+
+Prerequisites:
+
+- Set up and add envars to [Infisical Cloud](https://app.infisical.com)
+
+
+## Navigate to your project's integrations tab
+
+![integrations](../../images/integrations.png)
+
+## Enter your Railway API Token
+
+Obtain a Railway API Token in your Railway [Account Settings > Tokens](https://railway.app/account/tokens).
+
+![integrations railway dashboard](../../images/integrations-railway-dashboard.png)
+![integrations railway token](../../images/integrations-railway-token.png)
+
+<Note>
+    If this is your first time creating a Railway API token, then you'll be prompted to join
+    Railway's Private Boarding Beta program on the Railway Account Settings > Tokens page. 
+    
+    Note that Railway project tokens will not work for this integration since they don't work with
+    Railway's Public API.
+</Note>
+
+Press on the Railway tile and input your Railway API Key to grant Infisical access to your Railway account.
+
+![integrations railway authorization](../../images/integrations-railway-authorization.png)
+
+<Info>
+  If this is your project's first cloud integration, then you'll have to grant
+  Infisical access to your project's environment variables. Although this step
+  breaks E2EE, it's necessary for Infisical to sync the environment variables to
+  the cloud platform.
+</Info>
+
+## Start integration
+
+Select which Infisical environment secrets you want to sync to which Railway project and environment (and optionally service). Lastly, press create integration to start syncing secrets to Railway.
+
+![integrations create railway](../../images/integrations-railway-create.png)
+
+<Note>
+  Infisical integrates with both Railway's [shared variables](https://blog.railway.app/p/shared-variables-release) at the project environment level as well as service variables at the service level.
+  
+  To sync secrets to a specific service in a project, you can select a service from the Railway Service dropdown; otherwise, leaving it empty will sync secrets to the shared variables of that project.
+</Note>
+
+![integrations railway](../../images/integrations-railway.png)
+

docs/integrations/overview.mdx

@@ -18,6 +18,7 @@ Missing an integration? Throw in a [request](https://github.com/Infisical/infisi
 | [Vercel](/integrations/cloud/vercel)                           | Cloud     | Available   |
 | [Netlify](/integrations/cloud/netlify)                         | Cloud     | Available   |
 | [Render](/integrations/cloud/render)                           | Cloud     | Available   |
+| [Railway](/integrations/cloud/railway)                          | Cloud     | Available   |
 | [Fly.io](/integrations/cloud/flyio)                            | Cloud     | Available   |
 | [AWS Parameter Store](/integrations/cloud/aws-parameter-store) | Cloud     | Available   |
 | [AWS Secret Manager](/integrations/cloud/aws-secret-manager)   | Cloud     | Available   |

docs/mint.json

@@ -149,6 +149,7 @@
         "integrations/cloud/vercel",
         "integrations/cloud/netlify",
         "integrations/cloud/render",
+        "integrations/cloud/railway",
         "integrations/cloud/flyio",
         "integrations/cloud/azure-key-vault",
         "integrations/cicd/githubactions",