[Initiatives.wiki] Add some context for XML

[Alexander Mikhaylenko <alexm src gnome org>]

commit 621225c34d6cdf72fbf16adc320df6c90cc8af37
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Mon May 25 14:36:24 2020 +0000

    Add some context for XML

 View-switcher-pattern-migration.md | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)
---
diff --git a/View-switcher-pattern-migration.md b/View-switcher-pattern-migration.md
index 90ce229..86df217 100644
--- a/View-switcher-pattern-migration.md
+++ b/View-switcher-pattern-migration.md
@@ -69,7 +69,11 @@ After importing libhandy into the project, replace [`GtkStackSwitcher`](https://
 
 Set the [policy](https://gnome.pages.gitlab.gnome.org/libhandy/HdyViewSwitcher.html#HdyViewSwitcher--policy) 
to [`wide`](https://gnome.pages.gitlab.gnome.org/libhandy/HdyViewSwitcher.html#HdyViewSwitcherPolicy):
 ```xml
-<property name="policy">wide</property>
+<object class="HdyViewSwitcher">
+    <property name="visible">True</property>
+    <property name="stack">stack</property>
+    <property name="policy">wide</property>
+</object>
 ```
 
 ```c
@@ -83,10 +87,17 @@ While [`HdyViewSwitcher`](https://gnome.pages.gitlab.gnome.org/libhandy/HdyViewS
 For every page in the [`GtkStack`](https://developer.gnome.org/gtk3/stable/GtkStack.html), set an icon using 
the [`icon-name`](https://developer.gnome.org/gtk3/stable/GtkStack.html#GtkStack--c-icon-name) child property:
 
 ```xml
-<packing>
-    <property name="title">Example</property>
-    <property name="icon-name">face-smile-symbolic</property>
-</packing>
+<object class="GtkStack">
+    <child>
+        <object class="...">
+            ...
+        </object>
+        <packing>
+            <property name="title">Example</property>
+            <property name="icon-name">face-smile-symbolic</property>
+        </packing>
+    </child>
+</object>
 ```
 
 ```c
@@ -102,7 +113,11 @@ The recommended transition type to use with [`HdyViewSwitcher`](https://gnome.pa
 It can be achieved by setting the 
[`transition-type`](https://developer.gnome.org/gtk3/stable/GtkStack.html#GtkStack--transition-type) property 
to 
[`GTK_STACK_TRANSITION_TYPE_CROSSFADE`](https://developer.gnome.org/gtk3/stable/GtkStack.html#GtkStackTransitionType):
 
 ```xml
-<property name="transition-type">crossfade</property>
+<object class="GtkStack" id="stack">
+    <property name=visible">True</property>
+    <property name="transition-type">crossfade</property>
+    ...
+</object>
 ```
 
 ```c