Updated readme file

Author: adityasinghal26

Diff for: README.md

@@ -1,2 +1,16 @@
 # backstage-playground
 Playground for Backstage
+
+# Create Backstage app
+
+```
+npx @backstage/create-app@latest
+```
+
+## Run the app after git clone
+
+```
+yarn install
+
+yarn dev
+```