[DOCS] Add 6.8.18 release notes (#75938)

jrodewig · web-flow · commit 6f2ed7780372 · 2021-08-02T14:38:03.000-04:00
diff --git a/docs/reference/release-notes/6.8.asciidoc b/docs/reference/release-notes/6.8.asciidoc
@@ -3,6 +3,8 @@
 
 coming::[6.8.18]
 
+No significant changes.
+
 [[release-notes-6.8.17]]
 == {es} version 6.8.17
 
