Small change to two .md files (#235)

- Changing tree_traversal.md to show rust code

- Putting ###Haskell in correct place (currently it shows up after the Rust code)

Author: Wesley-Arrington

chapters/matrix_methods/gaussian_elimination/gaussian_elimination.md

@@ -259,6 +259,8 @@ In code, this looks like:
 [import:1-42, lang:"julia"](code/julia/gaussian_elimination.jl)
 {% sample lang="c" %}
 [import:13-44, lang:"c_cpp"](code/c/gaussian_elimination.c)
+{% sample lang="rs" %}
+[import:41-78, lang:"rust"](code/rust/gaussian_elimination.rs)
 {% endmethod %}
 
 As with all code, it takes time to fully absorb what is going on and why everything is happening; however, I have tried to comment the above psuedocode with the necessary steps. Let me know if anything is unclear!
@@ -274,6 +276,8 @@ Even though this seems straightforward, the pseudocode might not be as simple as
 [import:44-64, lang:"julia"](code/julia/gaussian_elimination.jl)
 {% sample lang="c" %}
 [import:46-58, lang:"c_cpp"](code/c/gaussian_elimination.c)
+{% sample lang="rs" %}
+[import:79-94, lang:"rust"](code/rust/gaussian_elimination.rs)
 {% endmethod %}
 
 Now, as for what's next... Well, we are in for a treat! The above algorithm clearly has 3 `for` loops, and will thus have a complexity of $$\sim O(n^3)$$, which is abysmal! If we can reduce the matrix to a specifically **tridiagonal** matrix, we can actually solve the system in $$\sim O(n)$$! How? Well, we can use an algorithm known as the _Tri-Diagonal Matrix Algorithm_ \(TDMA\) also known as the _Thomas Algorithm_.

chapters/tree_traversal/tree_traversal.md

@@ -235,8 +235,8 @@ MainClass.java
 {% sample lang="rs"%}
 ### Rust
 [import, lang:"rust"](code/rust/tree.rs)
-### Haskell
 {% sample lang="hs"%}
+### Haskell
 [import, lang:"haskell"](code/haskell/TreeTraversal.hs)
 {% endmethod %}