Implemented 'kill by PID' functionality

doc/source/netscript/basicfunctions/kill.rst

@@ -27,3 +27,22 @@ kill() Netscript Function
     The following will try to kill a script named *foo.script* on the current server that was ran with the arguments 1 and "foodnstuff"::
 
         kill("foo.script", getHostname(), 1, "foodnstuff");
+
+.. js:function:: kill(scriptPid)
+
+    :param number scriptPid: PID of the script to kill
+    :RAM cost: 0.5 GB
+
+    Kills the script with the specified PID. Killing a script by its PID will typically
+    have better performance, especially if you have many scripts running.
+
+    If this function successfully kills the specified script, then it will return true.
+    Otherwise, it will return false.
+
+    *Examples:*
+
+    The following example will try to kill the script with the PID 10::
+
+        if (kill(10)) {
+            print("Killed script with PID 10!");
+        }