New docs: Convert inline example code to use codeinclude macro

Improvement for the new mkdocs-based documentation.

Aim to replace the majority of inline code blocks in the docs with codeinclude macros, so that our examples are compiled and tested as part of the build.

This doesn't need to all be done in one PR - it probably ought to be split.

Pages that would benefit from this (in no particular order):

• docs/features/container_logs.md
• docs/features/commands.md
• docs/features/creating_container.md
• docs/features/creating_images.md
• docs/features/files.md
• docs/modules/docker_compose.md
• docs/modules/elasticsearch.md
• docs/modules/kafka.md
• docs/modules/vault.md
• docs/modules/webdriver_containers.md
• docs/test_framework_integration/junit_4.md
• docs/test_framework_integration/junit_5.md
• docs/test_framework_integration/spock.md
• docs/supported_docker_environment/logging_config.md

Start with one unchecked page, such as docs/features/container_logs.md, and compare it with the completed conversions in docs/modules/elasticsearch.md or docs/test_framework_integration/spock.md. Replace suitable inline examples with the codeinclude macro, then run the documentation build to confirm the examples compile and are tested.