Add solution for "zigzag conversion problem"

[v-280]

This issue aims to add a coding problem titled "ZIGZAG CONVERSION" along with its solution to the repository.

### PROBLEM STATEMENT The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)

P A H N A P L S I I G Y I R And then read line by line: "PAHNAPLSIIGYIR"

Write the code that will take a string and make this conversion given a number of rows:

string convert(string s, int numRows);

Example 1: Input: s = "PAYPALISHIRING", numRows = 3 Output: "PAHNAPLSIIGYIR"

Example 2: Input: s = "PAYPALISHIRING", numRows = 4 Output: "PINALSIGYAHRPI" Explanation: P I N A L S I G Y A H R P I

Constraints:

1 <= s.length <= 1000 s consists of English letters (lower-case and upper-case), ',' and '.'. 1 <= numRows <= 1000

I would like to contribute to this repo under hacktoberfest, kindly assign me this issue

[Aastha7078]

I Want to work this issue ,pls assign is to me .