docs: Warn users not to disable zip for macos

This warning was added in #6496 but removed by the very next release. It
is essential to warn users about this as disabling the `zip` target on
macos will prevent apps to auto-update.

docs/configuration/mac.md

@@ -8,8 +8,7 @@ The top-level [mac](configuration.md#Configuration-mac) key contains set of opti
 <p>Valid values are listed in <a href="https://developer.apple.com/library/ios/documentation/General/Reference/InfoPlistKeyReference/Articles/LaunchServicesKeys.html#//apple_ref/doc/uid/TP40009250-SW8">Apple’s documentation</a>.</p>
 </li>
 <li>
-<p><code id="MacConfiguration-target">target</code> String | <a href="/cli#targetconfiguration">TargetConfiguration</a> - The target package type: list of <code>default</code>, <code>dmg</code>, <code>mas</code>, <code>mas-dev</code>, <code>pkg</code>, <code>7z</code>, <code>zip</code>, <code>tar.xz</code>, <code>tar.lz</code>, <code>tar.gz</code>, <code>tar.bz2</code>, <code>dir</code>. Defaults to <code>default</code> (dmg and zip for Squirrel.Mac).</p>
-</li>
+<p><code id="MacConfiguration-target">target</code> String | <a href="/cli#targetconfiguration">TargetConfiguration</a> - The target package type: list of <code>default</code>, <code>dmg</code>, <code>mas</code>, <code>mas-dev</code>, <code>pkg</code>, <code>7z</code>, <code>zip</code>, <code>tar.xz</code>, <code>tar.lz</code>, <code>tar.gz</code>, <code>tar.bz2</code>, <code>dir</code>. Defaults to <code>default</code> (<code>dmg</code> and <code>zip</code> for Squirrel.Mac). Note: Squirrel.Mac auto update mechanism requires both <code>dmg</code> and <code>zip</code> to be enabled, even when only <code>dmg</code> is used. Disabling <code>zip</code> will break auto update in <code>dmg</code> packages.</p>
 <li>
 <p><code id="MacConfiguration-identity">identity</code> String | “undefined” - The name of certificate to use when signing. Consider using environment variables <a href="/code-signing">CSC_LINK or CSC_NAME</a> instead of specifying this option. MAS installer identity is specified in the <a href="/configuration/mas">mas</a>.</p>
 </li>