use language-invariant link to the usb-butter page

.gitlab-ci.yml

@@ -17,6 +17,9 @@ test:
   except:
   - butter-box
 
+# This includes 3 separate builds.
+# The main one is for the GitLab pages deployment.  It includes a simulated USB Butter drive.
+# The other two are for the downloadable zips of the site in English and Spanish.
 pages:
   stage: deploy
   script:
@@ -35,12 +38,13 @@ pages:
     - bundle exec jekyll build -d public
     - cd public
     - zip -r ../site-es.zip ./
-    # Now go build the site we actually want to deploy.
     - cd ..
     - git restore .
+    # Now go build the site we actually want to deploy.
     # simulate the drive being inserted
     - mv simulated-usb-butter usb-butter
     - "sed -i 's/^baseurl.*/baseurl: \"\\/butter-box-ui\"/' _config.yml"
+    - "sed -i 's/^usb_butter_url.*/usb_butter_url: \"\\/usb-butter\"/' _config.yml"
     - bundle exec jekyll build -d public
     # Now move the zip into the public dir so it gets served.
     - mv ./site-en.zip ./public/site-en.zip

_config.yml

@@ -2,6 +2,7 @@ title: Butter | Life without internet made smoother.
 description: >- # this means to ignore newlines until "baseurl:"
   Life without internet made smoother. Get access to tools that help.
 baseurl: "" # the subpath of your site, e.g. /blog
+usb_butter_url: "/usb-butter" # the language-invariant location of the USB Butter page
 url: "" # the base hostname & protocol for your site, e.g. http://example.com
 twitter_username: Butter App
 github_username:  Butter App

index.html

@@ -7,7 +7,7 @@ layout: default
 <div class="container">
   <div class="content">
     <!-- Defaults to display: none; revealed via JS depending on USB insertion. -->
-    <a href="{{ site.baseurl }}/usb-butter" id="usb-butter" style="display: none;" data-url="{{ site.baseurl }}/usb-butter">
+    <a href="{{ site.usb_butter_url }}" id="usb-butter" style="display: none;" data-url="{{ site.usb_butter_url }}">
       <div class="card">
           <img src="{{ site.baseurl }}/assets/images/explore-icon.png" alt="Explore Icon" class="card-icon-big">
           {% t explore %}