Added c lenguage hello world (freeCodeCamp#324)

* Added the Hello World in C

* Formated headers, and organized content

* Update index.md

Added a new line

src/pages/c/index.md

@@ -0,0 +1,65 @@
+---
+title: C
+---
+
+# Hello World! - Your first C Program
+
+## What is C?
+
+C is a general purpose programming language which was invented by Dennis Ritchie between 1969 and 1973 at Bell Labs, and it has been used to develop the Linux Kernel. 
+
+It was designed to provide low-level access to memory, to provide language constructs that map efficiently to machine instructions, and to require minimal run-time support. Along with C++ is widely used for micro controler programming and IOT such as [Arduino](https://www.arduino.cc/).
+
+ ## Hello world in C
+```C
+#include <stdio.h>
+
+int main(void)
+{
+    printf("hello, world\n");
+    return 0;
+}
+```
+
+Let's break down the program step by step.
+
+First we have:
+```C
+#include <stdio.h>
+```
+Which is the command for the compiler to include the stdio library that contain among other things the "I/O" funtions such as printf.
+
+```C
+int main(void)
+{
+}
+```
+ This is the declaration of the *main funtion* that is the first piece of code that is going to be executed when you run the program. The *int* before *main* indicate that the funtion is going to return an integral number (usually 0) when it has finished it's execution and the *void* inside the parenthesis mean that the funtion doesn't take any parameters.Finally the *{ }* symbols mark the beginning and the end of the funtion.
+```C
+    printf("Hello World\n");
+```
+We arrive to the most important part of the program, the *printf( )* funtion which print the data passed as an argument into the screen.
+In this case we have *"Hello World \n"* where we use the *" "* to indicate that *Hello World* is a string (text) and *\n* to display a new line.Finally we end the line wiht a semicolon *;*
+
+Finally, we safely terminate the program with:
+
+```C
+return 0;
+```
+
+Be very carefull to add the *;* at the end of the statment because if you forget it the computer wouldn´t know where the command finish and the compiler would raise an error.
+
+## Additional considerations
+
+You may require some software to write and execute C/C++ code. I recommend using CodeBlocks for Windows and Linux, and XCode for Mac.
+
+ * For Windows: [Download Here](http://www.codeblocks.org/downloads/26)
+ Use the link with the GNU/GCC compiler for windows.
+
+* For Mac: [Download for Mac Here](https://developer.apple.com/xcode/)
+
+* For Linux install the build-essentials and codeblocks packages with the package manager of your distribution. 
+In Ubuntu, Debian and Linux Mint:
+```bash
+sudo apt-get install codeblocks build-essentials
+```