Update linear.md

Author: astonzhang

units/linear.md

@@ -17,9 +17,9 @@
 
 ## Content
 
-* [Linear Regression](https://d2l.ai/chapter_linear-neural-networks/linear-regression.html）
-* [Linear Regression Implementation from Scratch](https://d2l.ai/chapter_linear-neural-networks/linear-regression-scratch.html)
-* [Concise Implementation of Linear Regression](https://d2l.ai/chapter_linear-neural-networks/linear-regression-gluon.html)
+* [Linear Regression](https://d2l.ai/chapter_linear-networks/linear-regression.html）
+* [Linear Regression Implementation from Scratch](https://d2l.ai/chapter_linear-networks/linear-regression-scratch.html)
+* [Concise Implementation of Linear Regression](https://d2l.ai/chapter_linear-networks/linear-regression-gluon.html)
 
 
 ## Videos