Update `Display default` checkbox label

Replace label for `Show default properties` and add tooltip explaining
what this checkbox is used for

Test: Open winscope
Merged-In: I39de3e1d7c203d5273084bd54c4d2f749e8e6f5f
Change-Id: I39de3e1d7c203d5273084bd54c4d2f749e8e6f5f
diff --git a/tools/winscope/src/App.vue b/tools/winscope/src/App.vue
index 15dbde2..9d6a679 100644
--- a/tools/winscope/src/App.vue
+++ b/tools/winscope/src/App.vue
@@ -18,7 +18,12 @@
       <h1 class="md-title" style="flex: 1">{{title}}</h1>
 
       <div>
-          <md-checkbox v-model="store.displayDefaults">Display defaults</md-checkbox>
+          <md-checkbox v-model="store.displayDefaults">Show default properties
+            <md-tooltip md-direction="bottom">
+              If checked, shows the value of all properties.
+              Otherwise, hides all properties whose value is the default for its data type.
+            </md-tooltip>
+          </md-checkbox>
       </div>
 
       <input type="file" @change="onLoadFile" id="upload-file" v-show="false"/>