BLD Add DISTDIR variable. ### Description

Adds `DISTDIR` env variable that points to the directory where libraries should be copied to when building shared libraries with recipe.

### Checklists

- [x] Add new / update outdated documentation

queries:
  - exclude: py/import-and-import-from

extraction:
  cpp:
    prepare:
      packages:
        - python3-yaml

queries:
  - exclude: py/import-and-import-from

extraction:
  cpp:
    prepare:
      packages:
        - python3-yaml
