feat: add translate="no" attribute to block literal templates

This commit adds the `translate="no"` attribute to block literal templates to prevent machine translation tools from attempting to translate content within literal blocks.
Literal blocks are typically used for command output, log files, and other pre-formatted text where exact spacing and formatting must be preserved.

Changes include:
- Added `translate="no"` attribute to the <pre> element in block_literal.html.erb
- Added a comprehensive test in htmlbook_spec.rb to verify the attribute is correctly applied to literal blocks delimited with `....`

This change complements the previous commits that added the same attribute to:
1. Inline code elements (via inline_quoted.html.erb)
2. Code blocks (via block_listing.html.erb)

Together, these changes ensure that all code-like content throughout the documentation is excluded from translation by browser-based translation tools and other translation
services, preserving the integrity of code examples, command output, and other technical content.

Author: nadamsoreilly

htmlbook/block_literal.html.erb

@@ -1 +1 @@
-<%#encoding:UTF-8%><pre><%= content %></pre>
+<%#encoding:UTF-8%><pre translate="no"><%= content %></pre>

spec/htmlbook_spec.rb

@@ -303,6 +303,16 @@ def hello
 		html = Nokogiri::HTML(convert(" This is also a literal block."))
 		html.xpath("//pre").text.should == "This is also a literal block."
 	end
+	
+	it "should add translate='no' attribute to literal blocks" do
+		html = Nokogiri::HTML(convert("
+....
+This is text in a literal block
+that should not be translated.
+....
+"))
+		html.xpath("//pre/@translate").text.should == "no"
+	end
 
 	# Test block_math template
 	it "should convert math blocks" do