Migrate Sympy Lecture from the Intro Series (#284)

* add sympy

* update sympy exercise

* Update lectures/sympy.md

Co-authored-by: Smit Lunagariya <smitlunagariya.mat18@itbhu.ac.in>

* Update lectures/sympy.md

Co-authored-by: Smit Lunagariya <smitlunagariya.mat18@itbhu.ac.in>

* update stats

* remove user expressions

* Update lectures/sympy.md

Co-authored-by: zhc <79777246+HengchengZhang@users.noreply.github.com>

* try build without scaling headers

* draft of application section

* update exercise again

* proofread

* proofread changes

* Update lectures/sympy.md

Co-authored-by: mmcky <mmcky@users.noreply.github.com>

* update two sentences

* integrate feedbacks

---------

Co-authored-by: Smit Lunagariya <smitlunagariya.mat18@itbhu.ac.in>
Co-authored-by: zhc <79777246+HengchengZhang@users.noreply.github.com>
Co-authored-by: mmcky <mmcky@users.noreply.github.com>

Author: 4 people

lectures/_toc.yml

@@ -19,6 +19,7 @@ parts:
   - file: matplotlib
   - file: scipy
   - file: pandas
+  - file: sympy
 - caption: High Performance Computing
   numbered: true
   chapters: