Update git submodule in appveyor build and fix the repo url in contributing doc

Author: prajon84

CONTRIBUTING.md

@@ -5,7 +5,7 @@
 This repo contains the submodule `mauth-protocol-test-suite` so requires a flag when initially cloning in order to clone and init submodules.
 
 ```
-git clone --recurse-submodules [email protected]:mdsol/mauth-client-ruby.git
+git clone --recurse-submodules [email protected]:mdsol/mauth-client-dotnet.git
 ```
 
 If you have already cloned a version of this repo before the submodule was introduced then run

appveyor.yml

@@ -4,6 +4,8 @@ pull_requests:
 image: Visual Studio 2019
 init:
   - git config --global core.autocrlf true
+install:
+  - git submodule update --init --recursive
 nuget:
   disable_publish_on_pr: true
 build_script:
@@ -24,4 +26,4 @@ deploy:
     api_key:
       secure: npZx6kvkDjB9a+wz5PILhIAGZ3gnxOyBnsc05GPOywfpP9d3R72oetjaH2eInrko
     on:
-      appveyor_repo_tag: true
+      appveyor_repo_tag: true