docs: Add minimum node version v11 (#370)

docs/src/getting-started/installation.md

@@ -51,3 +51,9 @@ npm install -g @project-serum/anchor
 
 Make sure your `NODE_PATH` is set properly so that globally installed modules
 can be resolved.
+
+## Minimum version requirements
+
+| Build tool  | Version        |
+|:------------|:---------------|
+| Node.js     | v11.0.0        |

ts/package.json

@@ -10,7 +10,7 @@
     "access": "public"
   },
   "engines": {
-    "node": ">=10"
+    "node": ">=11"
   },
   "scripts": {
     "build": "rm -rf dist/ && yarn build:node",