Update README.md

Author: ericelliott

README.md

@@ -2,17 +2,18 @@
 
 A list of open source projects that students can contribute to for student projects. Please feel free to join an existing project and collaborate. All your contributions to any project you've collaborated on will count toward your student achievements.
 
+## Library Projects
 
-## react-pure-component-starter
+### react-pure-component-starter
 
-### [Update ESLint](https://github.com/ericelliott/react-pure-component-starter/issues/196) #easy
+#### [Update ESLint](https://github.com/ericelliott/react-pure-component-starter/issues/196) #easy
 
 ESLint has deprecated some old rules. Bring the `.eslintrc` up to date with the current rule names. Run `npm run lint` to spot failures, and correct the error messages.
 
 
-## rtype
+### rtype
 
-### [Runtime rtype parser](https://github.com/ericelliott/rtype/issues/62) #advanced
+#### [Runtime rtype parser](https://github.com/ericelliott/rtype/issues/62) #advanced
 
 Experience with compilers, type theory, language design would be helpful.
 
@@ -25,3 +26,8 @@ Useful background:
 If you're curious about types, see the [introduction to types](https://class.coursera.org/compilers/lecture/45) from the Stanford Compiler course.
 
 
+## App Projects
+
+### [CheckIn](https://github.com/learn-javascript-courses/checkin) #intermediate
+
+A simple app to keep track of what people on your teams are working on.