Add samples files from the OT repo

[shaneataylor]

To facilitate using the samples files for examples in the documentation, moving these files out of the dita-ot repo and into the docs repo.

[jelovirt]

@infotexture @robander this is your call, I have no strong feelings about samples, other than they should not be a submodule (due to added management complexity).

[infotexture]

👍 I'm inclined to merge this, as I think it makes sense to treat samples as part of the documentation (which references them) rather than as core OT code.

Per discussion in dita-ot/dita-ot#2205, this would make it easier for the docs team to maintain samples, generate new sample content and reference samples via <coderef>.

[infotexture]

@shaneataylor: This changes the path to samples in distribution packages to docsrc/samples.

Would you be able to extend this PR with a new commit that updates creating-an-ant-build-script.dita and using-dita-command.dita accordingly?

[shaneataylor]

@infotexture: Will do.

@jelovirt, @infotexture: What do you think about either updating the docs build to copy docsrc/samples to its accustomed location for increased findability, or making a samples symlink to docsrc/samples in the distros (although I'm not sure how to do this for Windows)?

[infotexture]

@shaneataylor: Thanks.

Not sure we really need to copy the content to its old location, as the docsrc/samples folder will be included in the distribution packages, plus any topics referenced there from the root map in docs would also appear in the output folder doc/samples.

Not sure how many people discover samples by peeking into distribution subfolders, but I think as long as the docs refer to the new location, we should be fine.

[shaneataylor]

@infotexture I updated the topics and I'm fine with the move from samples to docsrc/samples.