Update READMEs.

Author: trekhleb

README.md

@@ -79,10 +79,10 @@ a set of rules that precisely define a sequence of operations.
   * [Shellsort](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/sorting/shell-sort)
   * [Counting Sort](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/sorting/counting-sort)
   * [Radix Sort](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/sorting/radix-sort)
-* **Tree Searches**
+* **Trees**
   * [Depth-First Search](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/tree/depth-first-search) (DFS)
   * [Breadth-First Search](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/tree/breadth-first-search) (BFS)
-* **Graph Algorithms**
+* **Graphs**
   * [Depth-First Search](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/graph/depth-first-search) (DFS)
   * [Breadth-First Search](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/graph/breadth-first-search) (BFS)
   * [Dijkstra Algorithm](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/graph/dijkstra) - finding shortest path to all graph vertices
@@ -139,7 +139,7 @@ algorithm is an abstraction higher than a computer program.
   * [Bellman-Ford Algorithm](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/graph/bellman-ford) - finding shortest path to all graph vertices
 * **Backtracking** - similarly to brute force, try to generate all possible solutions, but each time you generate a solution test
 if it satisfies all conditions, and only then continue generating subsequent solutions. Otherwise, backtrack, and go on a 
-different path of finding solution
+different path of finding a solution
   * [Hamiltonian Cycle](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/graph/hamiltonian-cycle) - Visit every vertex exactly once
   * [N-Queens Problem](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/uncategorized/n-queens)
   * [Knight's Tour](https://github.com/trekhleb/javascript-algorithms/tree/master/src/algorithms/uncategorized/knight-tour)