chg: [user-manual] Added some examples of correlations.

Author: cedricbonhomme

content/user-manual/correlations/index.md

@@ -12,6 +12,8 @@ Vulnerability-Lookup not only retrieves vulnerability information from various s
 affected software, sightings, and other relevant metadata (Vulnrichment, CISA KEV).
 
 
+### Related vulnerabilities
+
 Related vulnerabilities are located in the container ``vulnerability-lookup:linked``:
 
 ```bash
@@ -26,7 +28,7 @@ $ curl --silent 'https://vulnerability.circl.lu/api/vulnerability/CVE-2015-2051?
 
 ```
 
-The correlations is based on the various sources used by the Vulnerability-Lookup installation:
+The correlations are based on the various sources used by the Vulnerability-Lookup installation:
 
 ```bash
 $ curl --silent 'https://vulnerability.circl.lu/api/vulnerability/CVE-2015-2051?with_linked=true' | jq '.["vulnerability-lookup:linked"] | keys'
@@ -99,4 +101,7 @@ $ curl --silent 'https://vulnerability.circl.lu/api/vulnerability/CVE-2015-2051?
     }
   ]
 ]
-```
+```
+
+
+### Sightings