copy volume data

src/docs/guides/environments.md

@@ -16,6 +16,8 @@ Railway supports complex development workflows through environments, giving you
 
    - **Empty Environment** creates an empty environment with no services.
 
+---
+
 ## Sync Environments
 
 You can easily sync environments to _import_ one or more services from one environment into another environment.
@@ -32,6 +34,8 @@ You can easily sync environments to _import_ one or more services from one envir
             layout="responsive"
             width={1108} height={770} quality={100} />
 
+---
+
 ## Enable PR Environments
 
 Railway can spin up a temporary environment whenever you open a Pull Request. To enable PR environments, go to your Project Settings -> Environments tab.
@@ -44,10 +48,22 @@ width={480} height={156} quality={80} />
 
 When enabled, a temporary environment is spun up to support the Pull Request deploy. These environments are deleted as soon as these PRs are merged or closed.
 
-### How Come my GitHub PR Won't Deploy?
+#### How Come my GitHub PR Won't Deploy?
 
 Railway will not deploy a PR branch from a user who is not in your team or invited to your project without their associated GitHub account.
 
+### Copy Volume Data
+
+When enabled, any volume data from the base environment is copied to a new PR Environment. This is particularly useful if you've setup a staging environment with some seed data and want it copied into your new PR Environment.
+
+Before using the feature, here are some things to consider:
+
+- If you're using this feature, we _strongly_ recommend against using a production environment as your base environment.
+- Using the Copy Volume Data feature means PR Environments will have a copy of your base environment data with no fancy modifications.
+  - For a Postgres database, that means the username/password of a PR Environment will have to be the same as the base environment.
+  - For others tools like Redis, this is not an issue.
+- If you're using [Railway's Postgres template](https://railway.app/template/postgres), we'll make sure that password in the PR Environment matches the base one.
+
 ### Bot PR Environments
 
 You can enable automatic PR environment creation for PRs opened by GitHub bots (Dependabot, Renovatebot) using the `Enable Bot PR Environments` toggle on the Environments tab in the Project Settings page.