Do initial setup for trees structure

Signed-off-by: Maisha Supritee Chowdhury <74114117+maishaSupritee@users.noreply.github.com>

Author: maishaSupritee

web/thesauruses/_meta/trees.json

@@ -0,0 +1,9 @@
+{
+  "meta": {
+    "structure": "trees",
+    "structure_name": "Trees"
+  },
+  "categories": {
+    
+  }
+}

web/thesauruses/meta_info.json

@@ -39,6 +39,7 @@
     "operators": "Logical and Mathematical/Arithmetic Operators",
     "queues_stacks": "Queues and Stacks",
     "rules_facts": "Rules and Facts",
-    "strings": "Strings"
+    "strings": "Strings",
+    "trees": "Trees"
   }
 }