Remove raw markdown output

I don't think it's ever been that useful. It was originally implemented
as kind of a test of what Hugo output formats were capable of. It waited
for the `ugly` option to get added in `outputFormats` and the novelty of
a new Hugo feature was part of the fun of it.

As mentioned in 7a65f92f53:

    I believe I originally added it because I thought it was somewhat
    hard to get from the "View history" commit list to the actual page
    but I feel like people who care enough to go looking for the source
    code will be willing to use GitHub to find the actual source file.

i18n/en.yaml

@@ -32,9 +32,6 @@ readingtime:
 edit_history:
   other: "Edit history"
 
-view_markdown:
-  other: "View raw"
-
 
 # Post count
 no_posts:
@@ -74,9 +71,6 @@ aria_rss_link:
 aria_post_meta_edit_history:
   other: "link to page edit history"
 
-aria_post_meta_view_markdown:
-  other: "link to view raw markdown code of page"
-
 aria_post_meta_categories:
   other: "categories"