Update README.md

Author: petercorke

README.md

@@ -224,7 +224,7 @@ end
 ```
 The switch statement is used to select the code according to the URL given, and other methods provide access to parameters of the HTTP request.
 <hr />
-![page1](doc/page1.png)
+![page1](https://github.com/petercorke/simple-threads-coder/blob/master/doc/page1.png)
 ```shell
 2018-09-16 15:54:28.635937 [user] user program starts
 2018-09-16 15:54:28.636843 [user] web server starting on port 8080
@@ -238,7 +238,7 @@ Note the arguements `?a=7&b=12` on the end of the URL. These are GET arguments o
 
 Note also, that log messages from the web server function are listed as coming from the `WEB` thread, which is created by `webserver()`.
 <hr />
-![page2](doc/page2.png)
+![page2](https://github.com/petercorke/simple-threads-coder/blob/master/doc/page2.png)
 
 ```shell
 2018-09-16 15:39:12.816790 [WEB] web: GET request using HTTP/1.1 for URL /page2 
@@ -260,7 +260,7 @@ The template file is sent to the browser with substitutions.  The  `page2.html`
 ```
 and the values of the fields of the struct `vals` are substituted for the corresonding named `TMPL_VAR` tags.
 <hr />
-![duck](doc/duck.png)
+![duck](https://github.com/petercorke/simple-threads-coder/blob/master/doc/duck.png)
 
 ```shell
 2018-09-16 15:36:08.881139 [WEB] web: GET request using HTTP/1.1 for URL /duck 
@@ -269,7 +269,7 @@ and the values of the fields of the struct `vals` are substituted for the corres
 ```
 The local file `duck.png` is sent to the browser as an `image/jpeg` filetype.
 <hr />
-![post](doc/post.png)
+![post](https://github.com/petercorke/simple-threads-coder/blob/master/doc/post.png)
 
 ```shell
 2018-09-16 16:32:00.035029 [user] web: GET request using HTTP/1.1 for URL /input