minor edit

introduction.md

@@ -117,10 +117,13 @@ sudo apt-get update -y
 sudo apt-get install -y libm4ri-dev
 ```
 
+
+## Documentation 
+The document for this package is available at [https://qec-pages.github.io/dist-m4ri/](https://qec-pages.github.io/dist-m4ri/)
+
 This file (`introduction.md`) is used as the main page for the doxygen documentation.
 
-# Documentation Syntax 
-## Formula syntax
+### Formula syntax
 
 Inline formula: here \f$ a \f$ is random variable. \f$J \in {-1,1} \f$, 
 and (display mode) \f[ x \in (0,\infty) \f]
@@ -130,12 +133,12 @@ $$ y=a \exp(-Jx) $$
 
 $single dollar sign$ is not supported for inline formulas
 
-## Code blocks
+### Code blocks
 
 A `Python` function can be defined as
 ```
 def add(a,b):
     return a+b
 ```
 
-## Inline code block `y=\exp(Jx)` is not supported in section titles, how about just use (method = 1)
+### Inline code block `y=\exp(Jx)` is not supported in section titles, how about just use (method = 1)