Fix typo in the macOS development snapshots date

Author: shahmishal

install/macos/index.md

@@ -52,7 +52,7 @@ Swift snapshots are prebuilt binaries that are automatically created from the br
   <li class="resource">
     <h3>release/6.0</h3>
     <p class="description" style="font-size: 14px;">
-      <time datetime="{{ xcode_6_0_builds.first.date | date_to_xmlschema }}" title="{{ xcode_6_0_builds.first.date | date: '%B %-d, %Y %l:%M %p (%Z)' }}">{{ xcode_dev_builds.first.date | date: '%B %-d, %Y' }}</time>
+      <time datetime="{{ xcode_6_0_builds.first.date | date_to_xmlschema }}" title="{{ xcode_6_0_builds.first.date | date: '%B %-d, %Y %l:%M %p (%Z)' }}">{{ xcode_6_0_builds.first.date | date: '%B %-d, %Y' }}</time>
     </p>
     <p class="description">
       Toolchain package installer (.pkg)