Add explicit install instructions for libxml2 on MacOS

Closes #1698

diff --git a/INSTALL.md b/INSTALL.md
index d036673b1ee1923bdffcdb8dfc36ab7cbd5cde15..c05ccdbba85aec170c4f5ab8f06ad43fab62baf4 100644 (file)
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -83,6 +83,7 @@ Installing other dependencies:
 * Install Homebrew from http://mxcl.github.io/homebrew/
 * Install the latest version of Ruby: `brew install ruby`
 * Install ImageMagick: `brew install imagemagick`
+* Install libxml2: `brew install libxml2 --with-xml2-config`
 * Install Bundler: `gem install bundler`
 
 Note that OS X does not have a /home directory by default, so if you are using the GPX functions, you will need to change the directories specified in config/application.yml.