docs: add a note about the single-file binaries

docs/installation.rst

@@ -74,6 +74,15 @@ and compare that to our latest release and review the change log (see links on
 our web site).
 
 
+Installation (binary)
+---------------------
+For some platforms we offer a ready-to-use standalone borg binary.
+
+It is supposed to work without requiring installation or preparations.
+
+Check https://github.com/borgbackup/borg/issues/214 for available binaries.
+
+
 Debian Jessie / Ubuntu 14.04 preparations (wheel)
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