Update README.md

testing/README.md

-# Requirements Specification
+# Requirements Specification(fx_s3132)
 
 ## 1. introduction
 ### - 1.1 purpose
@@ -6,7 +6,7 @@
   - This product is a kind of calculator that performs various operations related to fixed point number.
   - For fixed-point arithmetic, c langauge's math library and type conversion are required.
 
-### 1.2 concept
+### - 1.2 concept
 - 1.1.2 basic concept
   - To operate several calculation for fixed-point numebr type casting is essential.
   - Correct type conversion is very important in order to accurately calculate and avoid missing bits.
@@ -22,3 +22,11 @@
 
 ## 2. overall description
 ### - 2.1 product functions
+- 2.1.1 list of fuctions
+  - 2.1.1.1 stpe 1
+    - a. add
+       ~~~
+       #define fx_add(a, b) ((a)+(b))
+       ~~~
+       - to add two fixed point numbers there is no need to conversion of data type
+       - just add two fixed point numbers and return result
\ No newline at end of file