Added general recursion and python recursion

sheets/_python/recursion

@@ -0,0 +1,15 @@
+# For what Recursion is, please check recursion 
+
+# Simple Factorial Python Recursion 
+def factorial(n) : 
+    if n == 0 : 
+        return 1 
+    else : 
+        return n * factorial(n-1)
+
+# Simple Greatest Common Divisor Recursion 
+def gcd(x, y) : 
+    if y == 0 : 
+        return x 
+    else : 
+        return gcd(y, x%y) 

sheets/recursion

@@ -0,0 +1,11 @@
+# Recursion 
+# Def: "...is a method where the solution to a problem depends on solutions to smaller instance of the same problem.." - wiki
+# TL;DR: a function that calls itself inside its body. 
+
+# Recursive programs - Pseduocode 
+function factorial: 
+input: integer n such that n >= 0
+output: n * (n-1) * (n-2) * ... * 1 = n!
+
+    1. if n is 0,   return 1 
+    2. else,        return ( n * factorial(n-1) )