The end of one long README

Apparently we've reached the limit of GitHub rendering (512K).
Time to change the structure accordingly - exercises and questions
will move to sub-directories in the exercises directory.

This is the first patch in performing this transition.

scripts/count_questions.sh

@@ -1,5 +1,3 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
-# We dont care about non alphanumerics filenames so we just ls | grep to shorten the script.
-
-echo $(( $(grep \</summary\> -c README.md) + $(grep -i Solution README.md | grep \.md -c) ))
+echo $(( $(grep -E "\[Exercise\]|</summary>" -c README.md exercises/*/README.md | awk -F: '{ s+=$2 } END { print s }' )))