Update website

Author: sparkprime

doc/ref/stdlib.html

@@ -307,7 +307,7 @@ <h4 id="objectKeysValues">
     <div class="panel">
       <p>
         <em>
-          Available in upcoming release.
+          Available since version 0.20.0.
         </em>
       </p>
       <p>
@@ -416,7 +416,7 @@ <h4 id="objectKeysValuesAll">
     <div class="panel">
       <p>
         <em>
-          Available in upcoming release.
+          Available since version 0.20.0.
         </em>
       </p>
       <p>
@@ -1066,7 +1066,7 @@ <h4 id="isEmpty">
     <div class="panel">
       <p>
         <em>
-          Available in upcoming release.
+          Available since version 0.20.0.
         </em>
       </p>
       <p>
@@ -2730,7 +2730,7 @@ <h4 id="sum">
     <div class="panel">
       <p>
         <em>
-          Available in upcoming release.
+          Available since version 0.20.0.
         </em>
       </p>
       <p>
@@ -3073,7 +3073,7 @@ <h4 id="xor">
     <div class="panel">
       <p>
         <em>
-          Available in upcoming release.
+          Available since version 0.20.0.
         </em>
       </p>
       <p>
@@ -3100,7 +3100,7 @@ <h4 id="xnor">
     <div class="panel">
       <p>
         <em>
-          Available in upcoming release.
+          Available since version 0.20.0.
         </em>
       </p>
       <p>