[infer][PR] fix link to FAQ in issue template
[infer][PR] fix link to FAQ in issue template

Summary:
The current [link](http://fbinfer.com/support.html#troubleshooting) results in a 404 "page not found" error. Also updated to https since the website redirects to https anyway.
Pull Request resolved: https://github.com/facebook/infer/pull/1261

Reviewed By: ezgicicek

Differential Revision: D21763768

Pulled By: jvillard

fbshipit-source-id: 50a9bcf7a

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