Improve Docker Compose docs

[etrandafir93]

Restructure documentation for the Docker Compose module, focusing on:

• focus on ComposeContainer instead of DockerComposeContainer as the primary source of examples.
  (current doc uses DockerComposeContainer in the majority of the code snippets)

• keep the code samples independent from the JUnit execution
  (the code examples include JUnit4's @ClassRule)

• use MkDocsfor the code snippets wherever possible
  (currently, the code samples are written as code blocks in markdown, instead of using MkDocs)

• add links to Javadoc and to other documentation pages wherever possible

Page to be modified: https://java.testcontainers.org/modules/docker_compose/

[eddumelendez]

I think we can use existing examples instead of adding new test just for docs.

[etrandafir93]

@eddumelendez - I've pushed some changes now, trying to make as much as possible from the existing tests

[eddumelendez]

Thanks for the update. Please, follow https://sembr.org/ and let's instead highlight only or point to our own documentation rather than javadoc.io.

[eddumelendez]

Suggested change

	The [`ComposeContainer`](http://static.javadoc.io/org.testcontainers/testcontainers/{{ latest_version }}/org/testcontainers/containers/ComposeContainer.html) leverages [Compose V2](https://www.docker.com/blog/announcing-compose-v2-general-availability/), making it easy to use the same dependencies from the development environment within tests.
	The `ComposeContainer` leverages [Compose V2](https://www.docker.com/blog/announcing-compose-v2-general-availability/), making it easy to use the same dependencies from the development environment within tests.

[etrandafir93]

@eddumelendez, when you have a few minutes, can you please let me know if I can help with anything else here? - cheers :)

[eddumelendez]

Thanks for your contribution, @etrandafir93 ! and sorry for the delay.