minor fix

Author: ZiniuYu

docs/source/index.rst

@@ -8,7 +8,6 @@ Linear Algebra Notes
 
 Study notes of Introduction to Linear Algebra, 5th Edition by Gilbert Strang
 
-
 .. toctree::
    :maxdepth: 2
    :caption: Contents:
@@ -23,7 +22,6 @@ Study notes of Introduction to Linear Algebra, 5th Edition by Gilbert Strang
    chap8/index8
    chap9/index9
    chap12/index12
-   about
 
 .. Indices and tables
 .. ==================