Fix asciidoc syntax

Fixes #57

Thank you https://github.com/LenKiMo

basics.md

@@ -307,7 +307,7 @@ Here's how this program works. First, we assign the literal constant value `5` t
 
 Then we add `1` to the value stored in `i` and store it back. We then print it and expectedly, we get the value `6`.
 
-Similarly, we assign the literal string to the variable +s+ and then print it.
+Similarly, we assign the literal string to the variable `s` and then print it.
 
 > **Note for static language programmers**
 > 

op_exp.md

@@ -194,11 +194,10 @@ Perimeter is 14
 
 **How It Works**
 
-The length and breadth of the rectangle are stored in variables by the same name. We use these to calculate the area and perimeter of the rectangle with the help of expressions. We store the result of the expression `length * breadth` in the variable +area+ and then print it using the +print+ function. In the second case, we directly use the value of the expression `2 * (length + breadth)`
-in the print function.
+The length and breadth of the rectangle are stored in variables by the same name. We use these to calculate the area and perimeter of the rectangle with the help of expressions. We store the result of the expression `length * breadth` in the variable `area` and then print it using the `print` function. In the second case, we directly use the value of the expression `2 * (length + breadth)` in the print function.
 
 Also, notice how Python _pretty-prints_ the output. Even though we have not specified a space between `'Area is'` and the variable `area`, Python puts it for us so that we get a clean nice output and the program is much more readable this way (since we don't need to worry about spacing in the strings we use for output). This is an example of how Python makes life easy for the programmer.
 
 ## Summary
 
-We have seen how to use operators, operands and expressions - these are the basic building blocks of any program. Next, we will see how to make use of these in our programs using statements. 
+We have seen how to use operators, operands and expressions - these are the basic building blocks of any program. Next, we will see how to make use of these in our programs using statements.