Classic legend tag

- this was removed in B4 but because we abuse it in all our projects I added it back

src/scss/_overwrites.scss

 // Things that originate from Bootstrap that we overwrite
+
+legend {
+    @extend legend;
+    margin-top: 1rem;
+    margin-bottom: 1rem;
+    border: 0;
+    border-bottom: 1px solid rgba(0,0,0,0.1)
+}
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