Update README.md

README.md

@@ -2,7 +2,7 @@
 
 Scientific calculator using [reverse polish notation](https://en.wikipedia.org/wiki/Reverse_Polish_notation) with complementary feature to write and execute user-written program easily.
 
-# Prerequisites (Linux)
+## Prerequisites (Linux)
 * C++ compiler (gcc, g++, ...)
 * Qt5
 * Cmake
@@ -13,18 +13,18 @@ To install qt5, go [here](https://www.qt.io/offline-installers) to download zip
 sudo apt-get install cmake g++
 ```
 
-# Build the application (Linux)
+## Build the application (Linux)
 ```
 mkdir build && cd build && cmake .. && cd ..
 cmake -S . -B build
 cmake --build build
 ```
 
-# How to run (Linux)
+## How to run (Linux)
 The executable file will be in the build directory:
 ```
 build/RPN_Calculator
 ```
 
-# Application Interface
+## Application Interface
 ![image](https://user-images.githubusercontent.com/40765474/111141668-18039f80-8584-11eb-84d6-31bc3c3a496c.png)