Copy docs for staable version to /docs/stable/ (#321)

diff --git a/site.sh b/site.sh
index 7c94a89..b466ad3 100755
--- a/site.sh
+++ b/site.sh
@@ -262,7 +262,7 @@
         version="$(basename -- "${doc_path}")"
         verbose_copy "${doc_path}" "dist/docs/${version}/"
     done
-    verbose_copy "docs-archive/$(cat docs-archive/stable.txt)" "dist/docs/stable/"
+    verbose_copy "docs-archive/$(cat docs-archive/stable.txt)/" "dist/docs/stable/"
     create_index dist/docs
 }