update docs

docs/src/math/introduction.md

@@ -3,12 +3,7 @@
 ## Introduction
 [B-spline](https://en.wikipedia.org/wiki/B-spline) is a mathematical object, and it has a lot of application. (e.g. Geometric representation: [NURBS](https://en.wikipedia.org/wiki/Non-uniform_rational_B-spline), Interpolation, Numerical analysis: [IGA](https://en.wikipedia.org/wiki/Isogeometric_analysis))
 
-In this page, we'll explain the mathematical definitions and properties of B-spline with Julia code.
-Before running the code in the following section, you need to import packages:
-```@example
-using BasicBSpline
-using Plots; plotly()
-```
+We will explain the mathematical definitions and properties of B-spline with Julia code in the following pages.
 
 ## Notice
 Some of notations in this page are our original, but these are well-considered results.