Fix license link in API docs (#3910)

Signed-off-by: Emmanuel Ferdman <emmanuelferdman@gmail.com>

src/NzbDrone.Host/Startup.cs

@@ -105,7 +105,7 @@ namespace NzbDrone.Host
                     License = new OpenApiLicense
                     {
                         Name = "GPL-3.0",
-                        Url = new Uri("https://github.com/Readarr/Readarr/blob/develop/LICENSE")
+                        Url = new Uri("https://github.com/Readarr/Readarr/blob/develop/LICENSE.md")
                     }
                 });
 

src/Readarr.Api.V1/openapi.json

@@ -5,7 +5,7 @@
     "description": "Readarr API docs",
     "license": {
       "name": "GPL-3.0",
-      "url": "https://github.com/Readarr/Readarr/blob/develop/LICENSE"
+      "url": "https://github.com/Readarr/Readarr/blob/develop/LICENSE.md"
     },
     "version": "1.0.0"
   },