feat(html): cache bust static files by adding hashes to file names

Closes rust-lang#1254

Author: notriddle

Cargo.lock

@@ -21,6 +21,7 @@ chrono = "0.4"
 clap = "2.24"
 env_logger = "0.7.1"
 handlebars = "3.0"
+hex = "0.4"
 lazy_static = "1.0"
 log = "0.4"
 memchr = "2.0"
@@ -30,6 +31,7 @@ regex = "1.0.0"
 serde = "1.0"
 serde_derive = "1.0"
 serde_json = "1.0"
+sha2 = "0.9"
 shlex = "0.1"
 tempfile = "3.0"
 toml = "0.5.1"

Cargo.toml

@@ -10,6 +10,7 @@ edition = "2018"
 [output.html]
 mathjax-support = true
 site-url = "/mdBook/"
+hash-files = true
 
 [output.html.playground]
 editable = true

guide/book.toml

@@ -528,6 +528,9 @@ pub struct HtmlConfig {
     /// The mapping from old pages to new pages/URLs to use when generating
     /// redirects.
     pub redirect: HashMap<String, String>,
+    /// If this option is turned on, "cache bust" static files by adding
+    /// hashes to their file names.
+    pub hash_files: bool,
 }
 
 impl Default for HtmlConfig {
@@ -554,6 +557,7 @@ impl Default for HtmlConfig {
             cname: None,
             livereload_url: None,
             redirect: HashMap::new(),
+            hash_files: false,
         }
     }
 }