Removes // from spaces link (#2537)

Author: KOTungseth

docs/en/glossary/terms/feature-controls.asciidoc

@@ -2,5 +2,5 @@
 [[glossary-feature-controls]] Feature Controls::
 Enables administrators to customize which features are available in each
 <<glossary-space,space>>. See
-{kibana-ref}//xpack-spaces.html#spaces-control-feature-visibility[Feature Controls].
+{kibana-ref}/xpack-spaces.html#spaces-control-feature-visibility[Feature Controls].
 //Source: Kibana