Added stack

Author: Hemav009

docs/dsa/stack/_category_.json

@@ -0,0 +1,8 @@
+{
+  "label": "Stack",
+  "position": 9,
+  "link": {
+    "type": "generated-index",
+    "description": "Stack is a linear data structure that follows LIFO principle"
+  }
+}

docs/dsa/stack/stack-using-array.md

@@ -1,10 +1,10 @@
 ---
 id: stack-in-dsa
 title: Stack Using Array
-sidebar_label: Stack
+sidebar_label: Stack Using Array
 sidebar_position: 1
-description: ""
-tags: [dsa, data-structures, stack]
+description: "Stack is a linear data structure that follows LIFO principle"
+tags: [dsa, data-structures, stack, LIFO]
 ---
 
 ### Introduction to Stack