amass, httprobe, sublist3r, theHarvester: add page (#4912)

pages/common/amass-track.md

@@ -0,0 +1,12 @@
+# amass track
+
+> Track differences between enumerations of the same domain.
+> More information: <https://github.com/OWASP/Amass/blob/master/doc/user_guide.md#the-track-subcommand>.
+
+- Show the difference between the last two enumerations of the specified domain:
+
+`amass track -dir {{path/to/database_directory}} -d {{domain_name}} -last 2`
+
+- Show the difference between a certain point in time and the last enumeration:
+
+`amass track -dir {{path/to/database_directory}} -d {{domain_name}} -since {{01/02 15:04:05 2006 MST}}`