user guide: DVC Files and Directories - 1.0 updates

[jorgeorpinel]

Completes #1367

See also iterative/example-repos-dev/pull/14

LOTS OF FILES CHANGES but these are the main ones:

• user-guide/dvc-files-and-directories.md now also explains both .dvc files and dvc.yaml.
• Most other changes are just the link update to the above guide.
• Changes in content\docs\user-guide\basic-concepts update the DVC-file term usage (rel: term: stop using "DVC-file" and "stage file" #1366).
• Avoid "meta" and "metafile" terms

---

• PENDING: After this PR and all the linked occurrences of "DVC-file" are updated to ".dvc file" (see term: stop using "DVC-file" and "stage file" #1366), update the link to the specific subsection of the docs, either #dvc-files or #dvcyaml-files.

[shcheklein]

It feels like we can do a section DVC Files and Directories with a few subsections inside:

1. .dvc directory
2. data .dvc files
3. pipelines .dvc.yaml`

In the index page we can show a tree of a DVC project for people to visualize what is going on.

WDYT?

[jorgeorpinel]

we can do a section DVC Files and Directories with a few subsections inside
From #1370 (comment)

Yep, that's is a good plan @shcheklein. Will do that. ✅

[shcheklein]

just one or two unresolved comments left? otherwise goo to go .. feel free to merge when you are done with them. Good stuff.

[jorgeorpinel]

OK! Double checked CI test fail and it's just the new link. Also looked at preview app and it looks fine. Merging.

[jorgeorpinel]

looked at preview app and it looks fine

p.s. it's getting pretty long though @shcheklein, should we make each file a sub-page? esp. when adding dvc.lock