tools: fix v doc not converting <s> in plain code blocks into encoded html entities in its .html output

cmd/tools/vdoc/html.v

@@ -617,7 +617,7 @@ fn (f &MdHtmlCodeHighlighter) transform_attribute(p markdown.ParentType, name st
 fn (f &MdHtmlCodeHighlighter) transform_content(parent markdown.ParentType, text string) string {
 	if parent is markdown.MD_BLOCKTYPE && parent == .md_block_code {
 		if f.language == '' {
-			return text
+			return html.escape(text)
 		}
 		output := html_highlight(text, f.table)
 		// Reset the language, so that it will not persist between blocks,

cmd/tools/vdoc/testdata/output_formats/README.md

@@ -150,4 +150,14 @@ A code block without a specific language should be rendered verbatim:
 └── main.v
 ```
 
+The s tags here in the code block, should be rendered verbatim, not interpreted as HTML ones:
+```
+h:m:s      // 5:02:33
+m:s.mi<s>  // 2:33.015
+s.mi<s>    // 33.015s
+mi.mc<ms>  // 15.007ms
+mc.ns<ns>  // 7.234us
+ns<ns>     // 234ns
+```
+
 The End.

cmd/tools/vdoc/testdata/output_formats/main.ansi

@@ -128,6 +128,14 @@ A code block without a specific language should be rendered verbatim:
 │       └── main.js
 └── main.v
 
+The s tags here in the code block, should be rendered verbatim, not interpreted as HTML ones:
+h:m:s      // 5:02:33
+m:s.mi<s>  // 2:33.015
+s.mi<s>    // 33.015s
+mi.mc<ms>  // 15.007ms
+mc.ns<ns>  // 7.234us
+ns<ns>     // 234ns
+
 The End.
 module main
     ## Description
@@ -281,6 +289,16 @@ The End.
     └── main.v
     ```
     
+    The s tags here in the code block, should be rendered verbatim, not interpreted as HTML ones:
+    ```
+    h:m:s      // 5:02:33
+    m:s.mi<s>  // 2:33.015
+    s.mi<s>    // 33.015s
+    mi.mc<ms>  // 15.007ms
+    mc.ns<ns>  // 7.234us
+    ns<ns>     // 234ns
+    ```
+    
     The End.
 
 const omega = 3 // should be first

cmd/tools/vdoc/testdata/output_formats/main.html

@@ -97,6 +97,12 @@ doc2 <span class="token operator">:=</span> toml<span class="token punctuation">
 │   └── js/
 │       └── main.js
 └── main.v
+</code></pre><p>The s tags here in the code block, should be rendered verbatim, not interpreted as HTML ones:</p><pre><code>h:m:s      // 5:02:33
+m:s.mi&lt;s&gt;  // 2:33.015
+s.mi&lt;s&gt;    // 33.015s
+mi.mc&lt;ms&gt;  // 15.007ms
+mc.ns&lt;ns&gt;  // 7.234us
+ns&lt;ns&gt;     // 234ns
 </code></pre><p>The End.</p>
 
 </section>

cmd/tools/vdoc/testdata/output_formats/main.text

@@ -150,6 +150,16 @@ module main
     └── main.v
     ```
     
+    The s tags here in the code block, should be rendered verbatim, not interpreted as HTML ones:
+    ```
+    h:m:s      // 5:02:33
+    m:s.mi<s>  // 2:33.015
+    s.mi<s>    // 33.015s
+    mi.mc<ms>  // 15.007ms
+    mc.ns<ns>  // 7.234us
+    ns<ns>     // 234ns
+    ```
+    
     The End.
 
 const omega = 3 // should be first