fix readme

README.md

@@ -4,14 +4,12 @@
 - `chmod 755 /etc/postfix /etc/postfix/main.cf /etc/postfix/dynamicmaps.cf`
 
 - `/etc/postfix/master.cf` example:
-
-> `spamassassin` host should resolve the IP of this container.
-
-```
-smtp      inet  n       -       n       -       -       smtpd
-  -o content_filter=spamassassin
-submission inet n       -       n       -       -       smtpd
-  -o content_filter=spamassassin
-spamassassin      unix  -       n       n       -       -       pipe
-  user=nobody argv=/usr/bin/spamc -d spamassassin -p 783 -e /usr/sbin/sendmail -oi -f ${sender} ${recipient}
-```
+  > `spamassassin` host should resolve the IP of this container.
+  ```
+  smtp      inet  n       -       n       -       -       smtpd
+    -o content_filter=spamassassin
+  submission inet n       -       n       -       -       smtpd
+    -o content_filter=spamassassin
+  spamassassin      unix  -       n       n       -       -       pipe
+    user=nobody argv=/usr/bin/spamc -d spamassassin -p 783 -e /usr/sbin/sendmail -oi -f ${sender} ${recipient}
+  ```