Fix typo in README.md (#80)

Author: Taormina

README.md

@@ -23,7 +23,7 @@ To run locally, you must first install node, npm, Ruby (we recommend RVM), ruby-
 Then, run:
 
 ```bash
-npm instal
+npm install
 bundle install
 ```
 
@@ -35,4 +35,4 @@ Then, run:
 bundle exec jekyll serve
 ```
 
-To start the local server.
+To start the local server.