Fix minor alignment and spacing issues

Author: jvendetti

app/views/mappings/index.html.haml

@@ -1,12 +1,12 @@
 - @title = "Mappings"
 %div#mappings_container.container-fluid
-  %h1.tab_header Mappings
-  %p.tab_description
+  %h2.mt-4 Mappings
+  %p
     = t('mappings.intro').html_safe
     = link_to(Rails.configuration.settings.links[:help_mappings],
               data: {controller: 'popup', action: 'click->popup#open'}, 'aria-label': 'View mappings help') do
       %i{class: 'fas fa-question-circle fa-lg ps-1', "aria-hidden": "true"}
-  %p#mappings_select
+  %p{id: 'mappings_select', class: 'mb-2'}
     - if @options.empty?
       No mappings available
     - else