Update README.md

Fixing links to make portable

README.md

@@ -9,7 +9,7 @@ This is a multipart lab, intended to be completed in order. We will be building
 Use the following links to complete this lab:
 
 * [Section 1](./instructions/section-01.md)
-* [Section 2](https://github.com/Zipcodecore/Product-Inventory-Lab/blob/master/instructions/section-02.md)
-* [Section 3](https://github.com/Zipcodecore/Product-Inventory-Lab/blob/master/instructions/section-03.md)
-* [Section 4](https://github.com/Zipcodecore/Product-Inventory-Lab/blob/master/instructions/section-04.md)
-* [Section 5](https://github.com/Zipcodecore/Product-Inventory-Lab/blob/master/instructions/section-05.md)
+* [Section 2](./instructions/section-02.md)
+* [Section 3](./instructions/section-03.md)
+* [Section 4](./instructions/section-04.md)
+* [Section 5](./instructions/section-05.md)