Use https in example GitHub Enterprise URL in Javadocs

[AlexLandau]

I just spent a few hours banging my head against some mysterious errors that were resolved by using an https-based URL instead of an http one. I had copied from the Javadocs example URL and replaced the domain name, and did not notice that it started with http:.

Use https: in the example instead, as that is more likely what people want.

Description

In the Javadocs for GitHubBuilder.withEndpoint, edit the example URL for GitHub Enterprise to use https: rather than http:.

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