Add MacPorts installation instructions (#544)

* Change OS X to macOS

* Add MacPorts installation instructions

Author: ryandesign

app/views/download/linux.volt

@@ -65,11 +65,14 @@ sudo yum install php-devel php-mysql gcc libtool pcre-devel
 # Suse
 yast2 -i php5-pear php5-devel php5-mysql gcc libtool pcre-devel
 
-# OS X (Homebrew)
+# macOS (Homebrew)
 brew tap homebrew/dupes
 brew tap homebrew/versions
 brew tap homebrew/php
-brew install php5x php5x-phalcon # php55, php56, ...</code></pre>
+brew install php5x php5x-phalcon # php55, php56, ...
+
+# macOS (MacPorts)
+sudo port install php73-phalcon # php72, php71, php56, ...</code></pre>
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