Unstable doc generation causes lots of git diff noise

[AArnott]

Each time I build dotnet/Nerdbank.GitVersioning#171 I get different results in the generated documentation. For instance:

-public static int GetVersionHeight(this LibGit2Sharp.Branch branch, string repoRelativeProjectDirectory = null);
+public static int GetVersionHeight(this Branch branch, string repoRelativeProjectDirectory = null);

or

-[Newtonsoft.Json.JsonProperty(DefaultValueHandling = Newtonsoft.Json.DefaultValueHandling.Ignore)]
+[JsonProperty(/*Could not decode attribute arguments.*/)]

The differences may be based on whether I'm building Nerdbank.GitVersioning.csproj vs. building Cake.GitVersioning.csproj

As a result, I wouldn't want this generator running as part of my build because of all the git diff noise it would produce.