Added documenting comments

src/Graph.js

@@ -11,15 +11,34 @@ class GraphIndex {
         this._graph = Graph();
     }
 
+    /**
+     * Each project points to a database
+     * containing all the information about a project.
+     */
     addProject(cid) {
         this._graph.addNode(cid)
     }
 
+    /**
+     * A depedency is a directed edg
+     * from the project dependent on another project to that project.
+     *
+     * If project A dependes on B, an edge from A to B is added.
+     *
+     * The weight is in the interval 0,1 and indicates the probability
+     * that an error/bug/problem in the dependency causes an error/bug/problem
+     * in the dependent project.
+     */
     addDependency(dependent, dependency, weight) {
         this._graph.addEdge(dependent, depedency, weight)
     }
 
+    /**
+     * @returns {Array<string>} cids of the projects in the Graph.
+     */
     get projects() {
         return this._graph.nodes()
     }
+
+    depedencyBetween
 }