Add everforest theme in theme examples (#1873)

example/themes/everforest-dark.kdl

@@ -0,0 +1,15 @@
+themes {
+    everforest-dark {
+        bg: "#2b3339"
+        fg: "#d3c6aa"
+        black: "#4b565c"
+        red: "#e67e80"
+        green: "#a7c080"
+        yellow: "#dbbc7f"
+        blue: "#7fbbb3"
+        magenta: "#d699b6"
+        cyan: "#83c092"
+        white: "#d3c6aa"
+        orange: "#FF9E64"
+    }
+}

example/themes/everforest-light.kdl

@@ -0,0 +1,15 @@
+themes {
+    everforest-light {
+        bg: "#fff9e8"
+        fg: "#5c6a72"
+        black: "#5c6a72"
+        red: "#f85552"
+        green: "#8da101"
+        yellow: "#dfa000"
+        blue: "#3a94c5"
+        magenta: "#df69ba"
+        cyan: "#35a77c"
+        white: "#dfddc8"
+        orange: "#FF9E64"
+    }
+}