Issue #1067120 follow-up by DamienMcKenna: API docs for hook_taxonomy_term_view().

core/modules/taxonomy/taxonomy.api.php

@@ -224,6 +224,30 @@ function hook_taxonomy_term_delete(Drupal\taxonomy\Term $term) {
   db_delete('term_synoynm')->condition('tid', $term->tid)->execute();
 }
 
+/**
+ * Act on a taxonomy term that is being assembled before rendering.
+ *
+ * The module may add elements to $term->content prior to rendering. This hook
+ * will be called after hook_view(). The structure of $term->content is a
+ * renderable array as expected by drupal_render().
+ *
+ * @param $term
+ *   The term that is being assembled for rendering.
+ * @param $view_mode
+ *   The $view_mode parameter from taxonomy_term_view().
+ * @param $langcode
+ *   The language code used for rendering.
+ *
+ * @see hook_entity_view()
+ */
+function hook_taxonomy_term_view($term, $view_mode, $langcode) {
+  $term->content['my_additional_field'] = array(
+    '#markup' => $additional_field,
+    '#weight' => 10,
+    '#theme' => 'mymodule_my_additional_field',
+  );
+}
+
 /**
  * Alter the results of taxonomy_term_view().
  *