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- [x] Add new / update outdated documentation

package:
  name: bokeh
  version: 3.0.3
  top-level:
    - bokeh
requirements:
  run:
    - distutils
    - numpy
    - Jinja2
    - Pillow
    - python-dateutil
    - six
    - typing-extensions
    - pyyaml
source:
  sha256: d30e4f6220efc824c5da0dcb58138abed0e6a2d524c942409c8ca1098031e374
  url: https://files.pythonhosted.org/packages/e6/42/c5a47809557331cf15bc69c1aeff81480f6a5aaf320d101d67511413ae92/bokeh-3.0.3-py3-none-any.whl
about:
  home: https://github.com/bokeh/bokeh
  PyPI: https://pypi.org/project/bokeh
  summary: Interactive plots and applications in the browser from Python
  license: BSD-3-Clause

package:
  name: bokeh
  version: 3.0.3
  top-level:
    - bokeh
requirements:
  run:
    - distutils
    - numpy
    - Jinja2
    - Pillow
    - python-dateutil
    - six
    - typing-extensions
    - pyyaml
source:
  sha256: d30e4f6220efc824c5da0dcb58138abed0e6a2d524c942409c8ca1098031e374
  url: https://files.pythonhosted.org/packages/e6/42/c5a47809557331cf15bc69c1aeff81480f6a5aaf320d101d67511413ae92/bokeh-3.0.3-py3-none-any.whl
about:
  home: https://github.com/bokeh/bokeh
  PyPI: https://pypi.org/project/bokeh
  summary: Interactive plots and applications in the browser from Python
  license: BSD-3-Clause
