refactor(repo): move the KDE and macOS docs under docs/ (pure move)

komorebi-for-kde/docs/ -> docs/linux/
komorebi-for-mac/docs/ -> docs/macos/

The Windows docs stay where they are (docs/). Renames only, so links and include paths
that named the old directories are broken at this revision; they are fixed in the revision
that fixes the paths of the whole layout move.

docs/linux/cli/unstack.md

@@ -0,0 +1,10 @@
+```text
+Unstack the focused window
+
+Usage: unstack
+
+Options:
+  -h, --help
+          Print help
+
+```