improve the migration guide

Author: dobrac

template/migration.mdx

@@ -4,17 +4,36 @@ description: "How to migrate from the legacy template definition"
 icon: "forward-fast"
 ---
 
+We've made ready for you three ways how to migrate existing template to the new definition format.
+
+- Using the migration command (recommended)
+- Using the `fromDockerfile()` method to parse existing Dockerfile
+- Building the Docker image manually and using `fromImage()` method
+
+## Migration Command (Recommended)
+
 To migrate the existing template definition to the new format, follow these steps:
-1) Install the latest version of the [E2B CLI](https://e2b.dev/docs/cli)
-2) Navigate to the folder of your existing template definition (where you have `e2b.toml` and `e2b.Dockerfile` files).
-3) Run the migration command:
-```bash
-e2b template migrate
-```
-4) Follow the prompts to complete the migration process.
-5) Done
 
-## Generated Output
+<Steps>
+    <Step title="Install E2B CLI">
+        Install the latest version of the [E2B CLI](https://e2b.dev/docs/cli)
+    </Step>
+    <Step title="Navigate to your template folder">
+        Navigate to the folder of your existing template definition (where you have `e2b.toml` and `e2b.Dockerfile` files).
+    </Step>
+    <Step title="Run migration command">
+    ```bash
+    e2b template migrate
+    ```
+    </Step>
+    <Step title="Follow the prompts">
+        Follow the prompts to complete the migration process.
+    </Step>
+    <Step title="Done">
+    </Step>
+</Steps>
+
+### Generated Output
 The migration command generates three files (based on the selected language).
 
 
@@ -33,3 +52,58 @@ build_prod.py - Production build script
 ```
 
 </CodeGroup>
+
+
+## Using `fromDockerfile()` Method
+
+If you want to keep using Dockerfile for your template, you can use the `fromDockerfile()` method.
+We'll automatically parse the Dockerfile for you and build the template based on it.
+You can find more at [Base Image](/template/customization/base-image#parsing-existing-dockerfiles).
+
+<CodeGroup dropdown>
+
+```typescript template.ts
+import { Template } from "e2b";
+
+const template = Template()
+  .fromDockerfile(dockerfileContent);
+```
+```python template.py
+from e2b import Template
+
+template = (
+    Template()
+    .from_dockerfile(dockerfile_content)
+)
+```
+
+</CodeGroup>
+
+After the template definition, you can create the build scripts as described in the [Quickstart](/template/quickstart#create-a-development-build-script) section.
+
+
+## Using `fromImage()` Method
+
+If you already have a Docker image built, or you want to keep building the Docker image yourself you can use the `fromImage()` method.
+Simply build the Docker image for the `linux/amd64` platform, push it to a registry of your choice and reference the image tag in the `fromImage()` method.
+You can also specify credentials for private registries as described in the [Base Image](/template/customization/base-image#custom-base-image) section.
+
+
+<CodeGroup dropdown>
+
+```typescript template.ts
+import { Template } from "e2b";
+
+const template = Template()
+  .fromImage("image-tag");
+```
+```python template.py
+from e2b import Template
+
+template = (
+    Template()
+    .from_image("image-tag")
+)
+```
+
+</CodeGroup>