Comment to not use any existing crates

hw2/task1/README.md

 
 Calculate the Hamming difference between two DNA strands by implementing the
 library function *hamming_distance(s1: &str, s2: &str) -> Result<usize,
-String>*.
+String>*. Do not use any crates.
 
 A mutation is simply a mistake that occurs during the creation or copying of a
 nucleic acid, in particular DNA. Because nucleic acids are vital to cellular

hw2/task3/README.md

 Compute Pascal's triangle up to a given number of rows. Create the new type
 *PascalsTriangle* and implement the methods *new()* and *rows()*. See the
 `tests/task3.rs` for more informationen about parameters and returns of the
-methods.
+methods. Do not use any crates.
 
 In Pascal's Triangle each number is computed by adding the numbers to the right
 and left of the current position in the previous row.