Theme: Use sentence case in English i18n strings

The most notable change is that "Top of Page" has been renamed to "Top of page". That'll impact all content page templates.

Author: EricDunsworth

site/data/i18n/en.json

@@ -8,7 +8,7 @@
   "tmpl-promo-title": "Promotions",
   "tmpl-feedback": "Report a problem on this page",
   "tmpl-gc-ca": "Canada.gc.ca",
-  "tmpl-toppage": "Top of Page",
+  "tmpl-toppage": "Top of page",
   "tmpl-share-page": "Share this page",
   "tmpl-about-government": "About government",
   "dlg-close": "Close dialog box",
@@ -150,7 +150,7 @@
   "menu-main-health-link-9": "https://www.canada.ca/en/services/health/health-system-services.html",
   "menu-main-health-text-10": "Science, research and data",
   "menu-main-health-link-10": "https://www.canada.ca/en/services/health/science-research-data.html",
-  "menu-main-taxes-text-1": "Income Tax",
+  "menu-main-taxes-text-1": "Income tax",
   "menu-main-taxes-link-1": "https://www.canada.ca/en/services/taxes/income-tax.html",
   "menu-main-taxes-text-2": "GST/HST",
   "menu-main-taxes-link-2": "https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/gst-hst-businesses.html",
@@ -218,7 +218,7 @@
   "so-youtube1": "[First YouTube account title]",
   "so-youtube2": "[Second YouTube account title]",
   "so-youtube3": "[Third YouTube account title]",
-  "so-rss": "RSS Feed",
+  "so-rss": "RSS feed",
   "so-email": "Email subscription",
   "de-title": "Features",
   "de-title-link": "[Feature hyperlink text]",
@@ -250,7 +250,7 @@
   "corp-info-list-item8":"Service performance reporting",
   "corp-info-job":"Minister",
   "corp-info-job-management":"Management",
-  "corp-info-job-org-head":"Organization Head",
+  "corp-info-job-org-head":"Organization head",
   "corp-info-institution-name":"[(Honourable) first and last name of Minister]",
   "corp-info-organization-name":"[Chairperson]",
   "corp-info-title": "Minister's official title",