Adjust for gofmt changes in 1.19

In 1.19, gofmt slightly changes how comments are formatted; a blank `//` is
inserted before `//go:embed` directives.

To accommodate for that in generate.go, treat empty comment lines as
part of docs segments.

examples/embed-directive/embed-directive.go

@@ -14,16 +14,19 @@ import (
 // `embed` directives accept paths relative to the directory containing the
 // Go source file. This directive embeds the contents of the file into the
 // `string` variable immediately following it.
+//
 //go:embed folder/single_file.txt
 var fileString string
 
 // Or embed the contents of the file into a `[]byte`.
+//
 //go:embed folder/single_file.txt
 var fileByte []byte
 
 // We can also embed multiple files or even folders with wildcards. This uses
 // a variable of the [embed.FS type](https://pkg.go.dev/embed#FS), which
 // implements a simple virtual file system.
+//
 //go:embed folder/single_file.txt
 //go:embed folder/*.hash
 var folder embed.FS

examples/embed-directive/embed-directive.hash

@@ -1,2 +1,2 @@
-53a5e68182be7308ddb35cc209e6b905c5b9c713
-p6JB_5z1IBJ
+69526bd78ac861c85bb12b96e9f1273e8aecc5a6
+6m2ll-D52BB

public/embed-directive

@@ -35,7 +35,7 @@ build time. Read more about the embed directive
 
           </td>
           <td class="code leading">
-            <a href="https://go.dev/play/p/p6JB_5z1IBJ"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
+            <a href="https://go.dev/play/p/6m2ll-D52BB"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
           <pre class="chroma">
 <span class="kn">package</span> <span class="nx">main</span>
 </pre>

tools/generate.go

@@ -95,8 +95,8 @@ func debug(msg string) {
 	}
 }
 
-var docsPat = regexp.MustCompile("^\\s*(\\/\\/|#)\\s")
-var dashPat = regexp.MustCompile("\\-+")
+var docsPat = regexp.MustCompile(`^(\s*(\/\/|#)\s|\s*\/\/$)`)
+var dashPat = regexp.MustCompile(`\-+`)
 
 // Seg is a segment of an example
 type Seg struct {