Add clean: Cleanup of usage traces to ~/.ssh/known_hosts file.

docs/complianced_image/AMI/how_to_creating_and_making_an_AMI_public.mkd

@@ -120,6 +120,7 @@ Use the following guidelines to reduce the attack surface and improve the reliab
 
 #### Clear the current log:
 ```
+$ echo > ~/.ssh/known_hosts
 # find /var/log/ -name "*.log" -exec shred -u {} \; 
 # find /var/log/ -name "*.log.*" -exec shred -u {} \; 
 # find / -name "authorized_keys" -exec shred -u {} \; 

docs/complianced_image/QEMU/how_to_creating_and_making_a_QEMU_img_for_debian9.mkd

@@ -123,6 +123,7 @@ $ cd /opt/harbian-audit-master/etc/conf.d
 
 #### Final fix  
 ```
+$ echo > ~/.ssh/known_hosts
 $ cd /opt/harbian-audit-master 
 # sed -i 's/^status=.*/status=enabled/' etc/conf.d/8.1.35_freeze_auditd_conf.cfg
 # sed -i 's/^status=.*/status=enabled/' etc/conf.d/8.4.1_install_aide.cfg