Add bit counter function.

Author: trekhleb

src/algorithms/math/bits/README.md

@@ -122,10 +122,10 @@ This method counts the number of set bits in a number using bitwise operators.
 The main idea is that we shift the number right by one bit at a time and check
 the result of `&` operation that is `1` if bit is set and `0` otherwise.
 
-``
+```text
 Number: 5 = 0b0101
 Count of set bits = 2
-``
+```
 
 > See `countSetBits` function for further details.