refactor: add .section-title (#36)

For the small title before the card

Remove .widget-title, .archive-date, .taxonomy-type from SCSS, as they all share the same style.

assets/scss/partials/layout/archives.scss

@@ -1,15 +1,5 @@
 .archives-group {
     margin-bottom: var(--section-separation);
-    .archives-date {
-        text-transform: uppercase;
-        margin-bottom: 10px;
-        font-size: 1.6rem;
-        font-weight: bold;
-
-        a {
-            color: var(--body-text-color);
-        }
-    }
 }
 
 .template-archives {

assets/scss/partials/layout/taxonomy.scss

@@ -1,11 +1,3 @@
-.taxonomy-type {
-    text-transform: uppercase;
-    color: var(--body-text-color);
-    font-weight: bold;
-    margin-bottom: 5px;
-    font-size: 1.6rem;
-}
-
 .taxonomy-card {
     border-radius: var(--card-border-radius);
     background-color: var(--card-background);