Set coursebook text fields to readonly instead of disabled

Disabled grays the text - readonly does not.
But readonly still allows to select the textfield.

aleksis/apps/alsijil/frontend/components/coursebook/documentation/LessonSummary.vue

@@ -16,7 +16,7 @@
         @focusout="save"
         @keydown.enter="saveAndBlur"
         :loading="loading"
-        :disabled="!documentation.canEdit"
+        :readonly="!documentation.canEdit"
       />
       <div class="d-flex flex-column align-start flex-grow-1">
         <v-chip
@@ -61,7 +61,7 @@
       :label="$t('alsijil.coursebook.summary.topic')"
       :value="documentation.topic"
       @input="topic = $event"
-      :disabled="!documentation.canEdit"
+      :readonly="!documentation.canEdit"
     />
     <v-textarea
       filled
@@ -70,7 +70,7 @@
       :label="$t('alsijil.coursebook.summary.homework.label')"
       :value="documentation.homework"
       @input="homework = $event"
-      :disabled="!documentation.canEdit"
+      :readonly="!documentation.canEdit"
     />
     <v-textarea
       filled
@@ -79,7 +79,7 @@
       :label="$t('alsijil.coursebook.summary.group_note.label')"
       :value="documentation.groupNote"
       @input="groupNote = $event"
-      :disabled="!documentation.canEdit"
+      :readonly="!documentation.canEdit"
     />
   </div>
 </template>