Rename exercises dir

Name it instead "topics" so it won't be
strange if some topics included "exercises" directory.

topics/shell/solutions/count_chars.md

@@ -0,0 +1,24 @@
+## Count Chars
+
+### Objectives
+
+1. Read input from the user until you get empty string
+2. For each of the lines you read, count the number of characters and print it
+
+### Constraints
+
+1. You must use a while loop
+2. Assume at least three lines of input
+
+### Solution
+
+```
+#!/usr/bin/env bash
+
+echo -n "Please insert your input: "
+
+while read line; do
+    echo -n "$line" | wc -c
+    echo -n "Please insert your input: "
+done
+```