[DOC] add warning about the dangers of doing salt-call state.highstate on your own machine (closes #149103)

1 
2      sudo salt-call saltutil.sync_modules
3      sudo salt-call saltutil.sync_states
4      sudo salt-call state.sls ami_builder
5 
6 +.. WARNING::
7 +    At this point, do NOT run a highstate  (salt-call state.highstate), as this
8 +    would modify multiple important system files from your system.
9 +
10  If you got only green and blue outputs, everything should be ok.
11 
12  You are now the proud owner of a variation.img file containing your
13  dear AMI, in `/mnt/output`.
14 

15  file by passing it as argument.
16 
17  The next step updates the salt states, if necessary by getting the necessary
18  files from the mercurial (hg) repository
19 
20 +.. WARNING::
21 +  The following commands replace the /etc/rc.local file on the machine as well as a few other
22 +  files (see the update.sls state file for more information), so do NOT do this
23 +  on your main machine !
24 +
25  .. code-block:: bash
26 
27    salt-call state.highstate
28    salt-call state.highstate
29