updated readme 4GeeksAcademy#3 and 4GeeksAcademy#7

Author: plucodev

exercises/03-What-is-a-function/README.md

@@ -1,6 +1,6 @@
 # `03` What is a function?
 
-You can see a function as a **fragment of code** encapsulated between curly brackets to be able to use it several times.
+You can see a function as a **fragment of code** we can use  several times.
 
 For example: If we want to get the sum of two numbers, we can declare a function called `sum` that returns the sum of number1 and number2:
 

exercises/07-lambda-function-two/README.md

@@ -1,7 +1,7 @@
 # `07` Lambda functions
 
 Take aim and note
-Arrow functions allows a short syntax for writing function expressions.
+Lambda functions allows a short syntax for writing function expressions.
 
 ```python
 multy = lambda x, y: x * y