Move /e2e -> /e2e-tests

e2e-tests/cypress/tests/fixtures/markdown/markdown_headings.html

@@ -0,0 +1 @@
+<h3 class="markdown__heading">Headings</h3><h1 class="markdown__heading">Heading 1 font size</h1><h2 class="markdown__heading">Heading 2 font size</h2><h3 class="markdown__heading">Heading 3 font size</h3><h4 class="markdown__heading">Heading 4 font size</h4><h5 class="markdown__heading">Heading 5 font size</h5><h6 class="markdown__heading">Heading 6 font size</h6>