Docs: Upgrade highlight.js to 9.0.0

with the following added languages in anticipation of document expansion:

    apache dockerfile dos less php powershell python tex yaml

To reproduce docs/static/js/highlight.pack.js on Debian/Ubuntu:

    $ sudo apt-get install nodejs npm
    $ wget https://github.com/isagalaev/highlight.js/archive/9.0.0.tar.gz
    $ tar xzf 9.0.0.tar.gz
    $ cd highlight.js-9.0.0/
    $ npm install
    $ nodejs tools/build.js markdown asciidoc xml css javascript \
      ini yaml json go bash diff dockerfile dos powershell makefile \
      apache nginx tex http php python ruby django haml handlebars \
      scss less coffeescript

Then, copy the resulting build/highlight.pack.js as well as
src/styles/monokai-sublime.css to the appropriate Hugo docs directories.

docs/static/css/monokai-sublime.css

@@ -0,0 +1,83 @@
+/*
+
+Monokai Sublime style. Derived from Monokai by noformnocontent http://nn.mit-license.org/
+
+*/
+
+.hljs {
+  display: block;
+  overflow-x: auto;
+  padding: 0.5em;
+  background: #23241f;
+}
+
+.hljs,
+.hljs-tag,
+.hljs-subst {
+  color: #f8f8f2;
+}
+
+.hljs-strong,
+.hljs-emphasis {
+  color: #a8a8a2;
+}
+
+.hljs-bullet,
+.hljs-quote,
+.hljs-number,
+.hljs-regexp,
+.hljs-literal,
+.hljs-link {
+  color: #ae81ff;
+}
+
+.hljs-code,
+.hljs-title,
+.hljs-section,
+.hljs-selector-class {
+  color: #a6e22e;
+}
+
+.hljs-strong {
+  font-weight: bold;
+}
+
+.hljs-emphasis {
+  font-style: italic;
+}
+
+.hljs-keyword,
+.hljs-selector-tag,
+.hljs-name,
+.hljs-attr {
+  color: #f92672;
+}
+
+.hljs-symbol,
+.hljs-attribute {
+  color: #66d9ef;
+}
+
+.hljs-params,
+.hljs-class .hljs-title {
+  color: #f8f8f2;
+}
+
+.hljs-string,
+.hljs-type,
+.hljs-built_in,
+.hljs-builtin-name,
+.hljs-selector-id,
+.hljs-selector-attr,
+.hljs-selector-pseudo,
+.hljs-addition,
+.hljs-variable,
+.hljs-template-variable {
+  color: #e6db74;
+}
+
+.hljs-comment,
+.hljs-deletion,
+.hljs-meta {
+  color: #75715e;
+}