Changing og:image to absolute URL

[sumitgpt]

Relative URL can cause problems with some website. Absolute URLs are recommended.

[daattali]

You're absolutely right. In fact I have an issue #254 open for this, because this needs to be fixed in multiple places. But it may not be as simple as simply adding {{ site.url }} as you have done; this will work for local images that are hosted in the repo, but it will break images that are external and use an http/https URL. Does that make sense?

[daattali]

@OCram85 this is that big issue that I told you about that I think is important :)

[OCram85]

@daattali I try working on a solution as soon as possible.

[daattali]

No rush!

[daattali]

@sumitgpt closing this PR since it does not solve the larger issue. Feel free to submit a PR for #254 :)