Link for "open issues" on line 90 of README is invalid. 

**Describe the bug**
Link for "open issues" on line 90 is invalid. 

**To Reproduce**
Click the link for "open issues" on line 90 

**Expected behavior**
No 404 error. 

**Screenshots**
If applicable, add screenshots to help explain your problem.

**Desktop (please complete the following information):**
 - Browser: FireFox
