Update README.rst to add do-not-strip-path option explanation.

slapos.extension.strip_/README.rst

@@ -46,3 +46,15 @@ Supported Options
   Path to ``strip`` program. Defaults to 'strip' which should work on
   any system that has the strip program available in the system
   ``PATH``.
+
+``do-not-strip-path``
+
+  A new-line separated list of absolute paths of the files you do not
+  want to strip.
+
+  An example::
+
+    [buildout]
+    do-not-strip-path =
+      ${bazel:location}/bin/bazel
+      ${another-part:location}/bin/dontstripbinary