Removed redundant OpenSearch link

For some reason, there were two of them.

From having a quick look at blame I see there alread was some [discussion](https://github.com/duckduckgo/duckduckgo-publisher/commit/79e3a364ab3a4e6a34911ea8a4c875cbb4609864#comments) about this but I do not understand what was the actual outcome, thus this pull request.