Shrink blank lines in docstrings and doc comments
Enable locally with compact-docstrings-mode:
(add-hook 'some-mode-hook #'compact-docstrings-mode)
Enable globally (in all programming modes) with global-compact-docstrings-mode:
(add-hook 'after-init-hook #'global-compact-docstrings-mode)
Enable compaction of all comments and strings by setting compact-docstrings-only-doc-blocks to nil. Change the compact line height by customizing compact-docstrings-face.