Add basic html template

src/app/comment/comment.component.html

+<form>
+  <mat-form-field>
+    <textarea matInput placeholder="add your comment" matTextareaAutosize matAutosizeMinRows="10"></textarea>
+  </mat-form-field>
+
+  <button mat-raised-button color="primary">back</button>
+  <button mat-raised-button color="primary">send</button>
+</form>
+