random: Fix right-open / left-open confusion for Random\IntervalBoundary

see php#3419

Author: TimWolla

reference/random/random.intervalboundary.xml

@@ -22,7 +22,7 @@
     <enumitem>
      <enumidentifier>ClosedOpen</enumidentifier>
      <enumitemdescription>
-      A left-open interval.
+      A right-open interval.
       The lower boundary is included in the interval,
       the upper boundary is not.
      </enumitemdescription>
@@ -39,7 +39,7 @@
     <enumitem>
      <enumidentifier>OpenClosed</enumidentifier>
      <enumitemdescription>
-      A right-open interval.
+      A left-open interval.
       The upper boundary is included in the interval,
       the lower boundary is not.
      </enumitemdescription>