Replace "Implicit Figures" with Shortcode (#1545)

Author: bash

Diff for: .github/newsletter-issue-template.md

@@ -115,8 +115,10 @@ Please use these templates as a starting point:
 ```md
 ### [Game name]
 
-![alt text](img)
-_optional image label_
+{{ image_figure(
+    alt="alt text"
+    src="img"
+    caption="optional image label") }}
 
 [Game name] ([GitHub], [Discord], [Twitter]) by [@nickname]
 is... {short project description in one sentence}.
@@ -133,8 +135,10 @@ _Discussions: [/r/rust_gamedev](link), [Twitter](link), [etc](link)_
 ```md
 ### [Article name]
 
-![alt text](img)
-_optional image label_
+{{ image_figure(
+    alt="alt text"
+    src="img"
+    caption="optional image label") }}
 
 [@nickname] published an [article] about...
 {overview what the resource is about}.

Diff for: .github/newsletter-template.md

@@ -50,8 +50,10 @@ Ideal section structure is:
 ```
 ### [Title]
 
-![image/GIF description](image link)
-_image caption_
+{{ image_figure(
+    alt="image/GIF description"
+    src="image link"
+    caption="image caption") }}
 
 A paragraph or two with a summary and [useful links].