Add Docker setup guide for application templates

[Copilot]

• Create src/guide/tutorial/docker.md - the Docker guide page covering all 5 required topics
• Update src/.vitepress/config.js to add the page to the Tutorial sidebar section
• Update src/guide/index.md to add a link in the Special topics section
• Update src/guide/tutorial/docker.md to document the new root .env.example for non-Docker development and the Docker env priority (yiisoft/app@a75636d)
• Update src/guide/start/creating-project.md to use the new .env.example → .env workflow, correct URL/port note, and name the .env.example file explicitly in prose

Original prompt

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This section details on the original issue you should resolve

<issue_title>Create a guide page about Docker setup in application templates</issue_title>
<issue_description>### Description

Create a user guide for Docker in https://github.com/yiisoft/app and https://github.com/yiisoft/app-api

Things to note especially:

1. make commands usage.
2. Contents of /docker overview.
3. Each .env purpose and examples.
4. compose.yml.
5. The idea of multi-stage builds.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Create a guide page about Docker setup in application templates #390

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[samdark]

@copilot update it considering yiisoft/app@a75636d

[Copilot]

@copilot update it considering yiisoft/app@a75636d

Done in 811b9cd. The guide now documents the new root-level .env.example / .env mechanism introduced by that commit:

• docker.md — Added a new ".env.example (project root)" subsection explaining it's for non-Docker local development, how src/bootstrap.php loads it via phpdotenv only when APP_ENV isn't already set in the process environment, and that Docker env vars always take precedence so both workflows coexist safely. Also notes phpdotenv is a dev dependency absent from production containers.
• creating-project.md — Updated the non-Docker run instructions to use cp .env.example .env && ./yii serve instead of the old APP_ENV=dev ./yii serve --port=80 prefix, and fixed the URL/port note to distinguish between the built-in server (:8080) and Docker (:80).

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[Copilot]

Pull request overview

Adds a new tutorial page documenting the Docker setup used by Yii application templates, and wires it into the guide navigation while updating the project creation workflow to reference .env.example.

Changes:

• Added a new Docker tutorial page covering directory layout, env files, Compose setup, multi-stage builds, and make targets.
• Added navigation entries for the new page (Guide index + VitePress sidebar).
• Updated “Creating a project” to reference the .env.example → .env workflow and clarified port configuration notes.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
src/guide/tutorial/docker.md	New Docker setup guide for yiisoft/app and yiisoft/app-api, including env/compose/multi-stage build and make command docs.
src/guide/start/creating-project.md	Updates local setup instructions to mention .env.example and improves the port-change note.
src/guide/index.md	Adds a “Docker in application templates” link under Special topics.
src/.vitepress/config.js	Adds the Docker guide page to the Tutorial sidebar section.

Comments suppressed due to low confidence (1)

src/guide/start/creating-project.md:48

• The instructions say to copy .env.example to .env, but the following shell snippet only shows ./yii serve. Add the cp .env.example .env step to the code block (or adjust the prose) so readers can follow the workflow without guessing.

Go into the newly created directory, copy `.env.example` to `.env`, and run:

```sh
./yii serve --port=80

</details>

[Copilot]

In the documented Dockerfile snippet, COPY .. /app will fail when the build context is the project root (as shown in the Compose example with context: ..) because Docker cannot copy files from outside the build context. Update the snippet to copy from within the build context (for example, COPY . /app) or adjust the documented build context accordingly.

Suggested change

	COPY .. /app
	COPY . /app

[Copilot]

This sentence says the Dockerfile defines four stages, but the table lists five (composer, base, dev, prod-builder, prod). Update the count (or clarify that composer is a helper stage) to avoid confusion.

[Copilot]

Spelling inconsistency: the docs elsewhere use American English "behavior"; this line uses "behaviour". Consider changing to "behavior" to keep wording consistent (and to avoid potential Vale style failures).

Suggested change

	The `deploy` block configures Docker Swarm behaviour: two replicas with a rolling `start-first` update
	The `deploy` block configures Docker Swarm behavior: two replicas with a rolling `start-first` update