Merge pull request #207 from nkm8/fixLink

Fix graphviz link

Author: jdsika

README.md

@@ -91,7 +91,7 @@ Detailed information about installation and usage of OSI can be found in the [Wi
 In order to generate the doxygen documentation for OSI, please follow the following steps:
 1. Install [Doxygen](http://www.stack.nl/~dimitri/doxygen/download.html), set an environmental variable 'doxygen' with the path to the binary file and add it to the PATH variable: `PATH += %doxygen%`.
 2. Download the [vg-1.5.0.zip](https://github.com/vgteam/vg/releases/tag/v1.5.0). Unpack and copy the content of folder /vg-1.5.0/contrib/proto2cpp to your desired `<path-to-proto2cpp.py>`
-3. Install [graphviz-2.38](http://www.graphviz.org/Download_windows.php ), set an environmental variable 'graphviz' with the path to the binary file and add it to the PATH variable: `PATH += %graphviz%`.
+3. Install [graphviz-2.38](https://graphviz.gitlab.io/_pages/Download/Download_windows.html), set an environmental variable 'graphviz' with the path to the binary file and add it to the PATH variable: `PATH += %graphviz%`.
 4. From the cmd navigate to the build directory and run:
 ```cmd
 cmake -DFILTER_PROTO2CPP_PY_PATH=<path-to-proto2cpp.py> <path-to-CMakeLists.txt>