add plugin to intercept markdown links

gatsby-config.js

@@ -135,5 +135,6 @@ module.exports = {
       },
     },
     'gatsby-plugin-react-helmet',
+    'gatsby-plugin-catch-links',
   ],
 };

package.json

@@ -27,6 +27,7 @@
     "flow-bin": "^0.56.0",
     "gatsby": "^1.9.9",
     "gatsby-link": "^1.6.9",
+    "gatsby-plugin-catch-links": "^1.0.9",
     "gatsby-plugin-feed": "^1.3.9",
     "gatsby-plugin-glamor": "^1.6.4",
     "gatsby-plugin-google-analytics": "^1.0.4",

yarn.lock

@@ -3836,6 +3836,12 @@ gatsby-module-loader@^1.0.5:
     babel-runtime "^6.26.0"
     loader-utils "^0.2.16"
 
+gatsby-plugin-catch-links@^1.0.9:
+  version "1.0.9"
+  resolved "https://registry.yarnpkg.com/gatsby-plugin-catch-links/-/gatsby-plugin-catch-links-1.0.9.tgz#454b19904e7fa891a2075ea56f9d5ff486324623"
+  dependencies:
+    babel-runtime "^6.26.0"
+
 gatsby-plugin-feed@^1.3.9:
   version "1.3.9"
   resolved "https://registry.yarnpkg.com/gatsby-plugin-feed/-/gatsby-plugin-feed-1.3.9.tgz#97c824b4dec65feec728cf27895ebff7a729f6e0"