Fix minor HTML tag mismatches

Fix some HTML tag mismatches and other glitches. These are minor, and don't appear to cause browsers any problems, but for the sake of correctness:
* A closing td which should be a closing div.
* A closing h3 for a corresponding h6
* Two tables with `<thead>` tag and missing `<tr>` around the `<th>` headings.

test change for thead fix

app/views/oauth2_applications/index.html.erb

@@ -7,10 +7,12 @@
 <% if @applications.length > 0 %>
   <table class="table table-borderless table-striped">
     <thead>
-      <th><%= t ".name" %></th>
-      <th><%= t ".permissions" %></th>
-      <th></th>
-      <th></th>
+      <tr>
+        <th><%= t ".name" %></th>
+        <th><%= t ".permissions" %></th>
+        <th></th>
+        <th></th>
+      </tr>
     </thead>
     <tbody>
       <%= render :partial => "application", :collection => @applications %>

app/views/oauth2_applications/show.html.erb

@@ -48,4 +48,4 @@
 <div>
   <%= link_to t(".edit"), edit_oauth_application_path(@application), :class => "btn btn-outline-primary" %>
   <%= link_to t(".delete"), oauth_application_path(@application), { :method => :delete, :class => "btn btn-outline-danger", :data => { :confirm => t(".confirm_delete") } } %>
-</td>
+</div>

app/views/oauth2_authorized_applications/index.html.erb

@@ -7,9 +7,11 @@
 <% if @applications.length > 0 %>
   <table class="table table-borderless table-striped">
     <thead>
-      <th><%= t ".application" %></th>
-      <th><%= t ".permissions" %></th>
-      <th></th>
+      <tr>
+        <th><%= t ".application" %></th>
+        <th><%= t ".permissions" %></th>
+        <th></th>
+      </tr>
     </thead>
     <tbody>
       <%= render :partial => "application", :collection => @applications %>

app/views/site/help.html.erb

@@ -16,7 +16,7 @@
             <a href='<%= t ".#{site}.url" %>'>
               <%= t ".#{site}.title" %>
             </a>
-          </h3>
+          </h6>
           <p class='card-text'><%= t ".#{site}.description" %></p>
         </div>
         <div class="card-footer">

test/controllers/oauth2_applications_controller_test.rb

@@ -51,7 +51,7 @@ class Oauth2ApplicationsControllerTest < ActionDispatch::IntegrationTest
     get oauth_applications_path
     assert_response :success
     assert_template "oauth2_applications/index"
-    assert_select "tr", 2
+    assert_select "tbody tr", 2
   end
 
   def test_new

test/controllers/oauth2_authorized_applications_controller_test.rb

@@ -33,7 +33,7 @@ class Oauth2AuthorizedApplicationsControllerTest < ActionDispatch::IntegrationTe
     get oauth_authorized_applications_path
     assert_response :success
     assert_template "oauth2_authorized_applications/index"
-    assert_select "tr", 2
+    assert_select "tbody tr", 2
   end
 
   def test_destroy
@@ -58,6 +58,6 @@ class Oauth2AuthorizedApplicationsControllerTest < ActionDispatch::IntegrationTe
     get oauth_authorized_applications_path
     assert_response :success
     assert_template "oauth2_authorized_applications/index"
-    assert_select "tr", 1
+    assert_select "tbody tr", 1
   end
 end