docs/features.md: add feature gifs for snippets and fill struct

Add gifs to the snippets and fill struct feature descriptions.

Change-Id: I0837204ad03fea90ea0e6def713b9c70942c2bca
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/284672
Trust: Suzy Mueller <suzmue@golang.org>
Trust: Hyang-Ah Hana Kim <hyangah@gmail.com>
Run-TryBot: Suzy Mueller <suzmue@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
diff --git a/docs/features.md b/docs/features.md
index 9b86647..23b9966 100644
--- a/docs/features.md
+++ b/docs/features.md
@@ -112,6 +112,8 @@
 
 Predefined snippets for quick coding. These snippets will appear as completion suggestions when you type. Users can also define their own custom snippets (see [Snippets in Visual Studio Code](https://code.visualstudio.com/docs/editor/userdefinedsnippets#_create-your-own-snippets)).
 
+<div style="text-align: center;"><img src="images/snippets-tys.gif" alt="Use the struct type snippet" style="width: 75%"> </div>
+
 ### Format and organize imports
 
 Format code and organize imports, either manually or on save. The code is formatted by the [`gofmt`](tools.md#formatting) tool, which is the standard for Go code. Imports are added automatically to your file via the [`goimports`](tools.md#formatting) tool, which is also an industry standard. By default, this extension also uses the [`goreturns`](tools.md#formatting) tool, which automatically fills in default return values for functions.
@@ -166,6 +168,8 @@
 
 Use the [`Go: Fill struct`](commands.md#fill-struct) command to automatically fill a struct literal with its default values. This command is provided by the [`fillstruct`](tools.md#fillstruct).
 
+<div style="text-align: center;"><img src="images/fillstructliterals.gif" alt="Fill struct literals" style="width: 75%"> </div>
+
 ## Diagnostics
 
 Learn more about [diagnostic errors](tools.md#diagnostics).
diff --git a/docs/images/fillstructliterals.gif b/docs/images/fillstructliterals.gif
new file mode 100644
index 0000000..9ea7fc2
--- /dev/null
+++ b/docs/images/fillstructliterals.gif
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diff --git a/docs/images/snippets-tys.gif b/docs/images/snippets-tys.gif
new file mode 100644
index 0000000..e67b1a9
--- /dev/null
+++ b/docs/images/snippets-tys.gif
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