update information about freebsd, add warning about selinux and (#183)

* update information about freebsd, add warning about selinux and modsecurity

* fix formatting

Author: xmacan

Diff for: General-Installing-Instructions.md

@@ -117,9 +117,10 @@ prepared. Both ways have few pros and cons:
   [Howto use ports](https://www.freebsd.org/doc/handbook/ports-using.html))
 
   ```sh
-  portsnap fetch extract
-  portsnap fetch update
-  cd /usr/ports/databases/mariadb102-server (or mysql57-server)
+  pkg install git
+  git clone https://git.FreeBSD.org/ports.git /usr/ports
+  git -C /usr/ports pull
+  cd /usr/ports/databases/mariadb106-server (or mysql80-server)
   make install
   cd /usr/ports/net-mgmt/cacti
   make install

Diff for: Requirements.md

@@ -21,6 +21,12 @@ Cacti requires that the following software is installed on your system.
   - Optional modules:
     - snmp (falls back to NetSNMP)
 
+- Problematic software and configuration
+  - On Linux OS do not turn on SELinux
+  - On web server do not turn on ModSecurity
+
+    SELinux and ModSecurity can cause problem with ICMP ping, socket connections, ...
+
 - MySQL 5.6 or MariaDB 5.5 or greater
   - Timezone support must be enabled
 

Diff for: Upgrading-Cacti-Under-FreeBSD.md

@@ -27,7 +27,9 @@
    or
 
    ```sh
-   shell> portsnap fetch update
+   shell> pkg install git
+   shell> git clone https://git.FreeBSD.org/ports.git /usr/ports
+   shell> git -C /usr/ports pull
    shell> cd /usr/ports/net-mgmt/cacti
    shell> make deinstall clean install
    ```
@@ -36,6 +38,7 @@
    recreate the folder and correct the permissions.
 
    ```sh
+   shell> cd /usr/local/share/cacti
    shell> mkdir cache
    shell> chown -R cacti cache
    ```