Docs: Programatically removing a Snackbar (MudBlazor#5016)

* added documentation for programatically remove snackbar

* updated text and highligthing

src/MudBlazor.Docs/Pages/Components/Snackbar/Examples/SnackbarRemoveExample.razor

@@ -0,0 +1,27 @@
+@namespace MudBlazor.Docs.Examples
+
+@inject ISnackbar Snackbar
+
+<MudButton Variant="Variant.Filled" Color="Color.Primary" OnClick="@Show">
+    Open Snackbar
+</MudButton>
+<MudButton Variant="Variant.Filled" Color="Color.Error" OnClick="@Hide">
+    Hide snackbar
+</MudButton>
+
+@code {
+    private Snackbar _snackbar;
+
+    void Show()
+    {
+        _snackbar = Snackbar.Add("Now click hide snackbar", Severity.Normal, config =>
+        {
+            config.VisibleStateDuration = int.MaxValue;
+        });
+    }
+
+	void Hide() {
+        if (_snackbar is null) return;
+        Snackbar.Remove(_snackbar);
+	}
+}

src/MudBlazor.Docs/Pages/Components/Snackbar/SnackbarPage.razor

@@ -144,5 +144,16 @@
             </SectionContent>
         </DocsPageSection>
 
+        <DocsPageSection>
+            <SectionHeader Title="Programmatically remove">
+                <Description>
+                    Using the injected ISnackbar, you can use the <CodeInline>.Remove</CodeInline> method to remove a Snackbar programmatically.
+                </Description>
+            </SectionHeader>
+            <SectionContent Code="SnackbarRemoveExample" ShowCode="false">
+                <SnackbarRemoveExample />
+            </SectionContent>
+        </DocsPageSection>
+
     </DocsPageContent>
 </DocsPage>