Add back to dataset list button => DONE

client/src/app/instance/doc/containers/doc.component.html

-<app-spinner *ngIf="attributeListIsLoading | async"></app-spinner>
+<div class="container">
+    <app-spinner *ngIf="attributeListIsLoading | async"></app-spinner>
 
-<div *ngIf="attributeListIsLoaded | async" class="container">
     <div class="jumbotron">
         <div class="row align-items-center">
             <div class="col-md-12 order-md-1 text-justify text-md-left pr-md-5">
@@ -29,9 +29,9 @@
                 </ul>
 
                 <app-output-list
-                    [datasetSelected]="datasetSelected | async"
-                    [attributeList]="attributeList | async"
-                ></app-output-list>
+                        [datasetSelected]="datasetSelected | async"
+                        [attributeList]="attributeList | async">
+                </app-output-list>
 
                 <h5>Operators</h5>
                 <table id="table">
@@ -168,4 +168,8 @@
             </div>
         </div>
     </div>
+
+    <button class="btn btn-outline-secondary mt-3">
+        <span class="fas fa-arrow-left"></span> Return to previous page
+    </button>
 </div>