docs: Add Dockerfile and docker build instructions

[juninhocruzg3]

add docker-compose.yml and Dockerfile to compile shaka inside container; reference it on docs;

Description

Many devs using Shaka and wishing to compile the library are required to install all prerequisites on their machine. For docker devs, this is extremely bad as it requires installing Java and Python on OS.
This commit adds a basic configuration for quick compilation via Docker, without requiring any other prerequisites. Improvements can be made in order to allow all Shaka workflow inside Docker.
Suggested in #181

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to
  not work as expected)
• This change requires a documentation update

Checklist:

• I have signed the Google CLA https://cla.developers.google.com
• My code follows the style guidelines of this project
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works [not applicable/not auto-testable]
• I have verified my change on multiple browsers on different platforms
• I have run ./build/all.py and the build passes
• I have run ./build/test.py and all tests pass

BEGIN_COMMIT_OVERRIDE
feat: Add Dockerfile and docker build instructions
END_COMMIT_OVERRIDE

[joeyparrish]

Thanks for contributing!

It seems like it should be relatively okay to run commands in this very temporary container as root. But it still bothers me that there is an error from generateLocalizations.py.

Can you provide details of the error? I'd like to try to help you solve it so that we can adopt a non-root solution here.

[juninhocruzg3]

I apologize for the delay in providing the error.
Proceeding the contribution, here's the error I get in non-root mode:

Successfully tagged docker_shaka-compiler:latest
Creating shaka-compiler ... done
Attaching to shaka-compiler
shaka-compiler    | Traceback (most recent call last):
shaka-compiler    |   File "/usr/src/app/build/all.py", line 150, in <module>
shaka-compiler    |     shakaBuildHelpers.run_main(main)
shaka-compiler    |   File "/usr/src/app/build/shakaBuildHelpers.py", line 374, in run_main
shaka-compiler    |     sys.exit(main(sys.argv[1:]))
shaka-compiler    |   File "/usr/src/app/build/all.py", line 92, in main
shaka-compiler    |     if not localizations.generate(parsed_args.force):
shaka-compiler    |   File "/usr/src/app/build/compiler.py", line 512, in generate
shaka-compiler    |     generateLocalizations.main(['--locales'] + locales)
shaka-compiler    |   File "/usr/src/app/build/generateLocalizations.py", line 255, in main
shaka-compiler    |     with open(args.output, 'wb') as f:
shaka-compiler    | FileNotFoundError: [Errno 2] No such file or directory: '/usr/src/app/dist/locales.js'
shaka-compiler exited with code 1

This time, I'll follow the github notifications in order to haven't a delay again.

[juninhocruzg3]

@joeyparrish , Is there any risk of this pull request being closed for update timeout or shouldn't I worry about time? Is there anything I can do in order to help to proceed this PR?

[juninhocruzg3]

I finally solved the problem to run as non-root user. @joeyparrish, I need a new review. No update is needed on my pull request:

add docker-compose.yml and Dockerfile to compile shaka inside container; reference it on docs;

Description

Many devs using Shaka and wishing to compile the library are required to install all prerequisites on their machine. For docker devs, this is extremely bad as it requires installing Java and Python on OS.
This commit adds a basic configuration for quick compilation via Docker, without requiring any other prerequisites. Improvements can be made in order to allow all Shaka workflow inside Docker.
Suggested in #181

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to
  not work as expected)
• This change requires a documentation update

Checklist:

• I have signed the Google CLA https://cla.developers.google.com
• My code follows the style guidelines of this project
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works [not applicable/not auto-testable]
• I have verified my change on multiple browsers on different platforms
• I have run ./build/all.py and the build passes
• I have run ./build/test.py and all tests pass

[joeyparrish]

Looks good. Thanks!