chg: [tools] updated sightings sources.

content/tools.md

@@ -20,10 +20,12 @@ A suite of sighting clients is already available to support this functionality:
 - **CISA KEV** - [Known Exploited Vulnerabilities (KEV) catalog](https://pypi.org/project/kevsight)
 - **RSS** - [Newspipe](https://github.com/cedricbonhomme/newspipe) is a web news aggregator capable to detect
   various types of security advisories within articles.
-
+- **GitHub Gist** - we are [monitoring](https://vulnerability.circl.lu/sightings/?query=gist.github) public Gists on Github.
 
 If you want to create your own sigthing tool, it's recommended to use [PyVulnerabilityLookup](https://github.com/cve-search/PyVulnerabilityLookup), a Python library to access Vulnerability-Lookup via its REST API.
 
+More information related to the sightings can be found in the [documentation](https://www.vulnerability-lookup.org/documentation/sightings.html).
+
 ## Libraries to access the Vulnerability-Lookup API
 
 - [PyVulnerabilityLookup](https://github.com/cve-search/PyVulnerabilityLookup) the official Python