docs: Fix link to settings_jsonschema.json
first, the link wasn't rendering because of a missing `(`
second, using "click here" as link text is not very usable for people with screen readers, this change improves accessibility.
"source": [
"## Method 3: Providing the spec as a dictionary\n",
"\n",
- "Ultimately, comparisons are specified as a dictionary which conforms to the formal `jsonschema` specification of the settings dictionary - see [here]https://github.com/moj-analytical-services/splink/blob/master/splink/files/settings_jsonschema.json) and [here](https://moj-analytical-services.github.io/splink/).\n",
+ "Ultimately, comparisons are specified as a dictionary which conforms to [the formal `jsonschema` specification of the settings dictionary](https://github.com/moj-analytical-services/splink/blob/master/splink/files/settings_jsonschema.json) and [here](https://moj-analytical-services.github.io/splink/).\n",
"\n",
"The library functions described above are convenience functions that provide a shorthand way to produce valid dictionaries.\n",
"\n",
