feat: add plantuml to support charts textcomplete list

Signed-off-by: Max Wu <jackymaxj@gmail.com>

Author: jackycute

public/js/index.js

@@ -97,7 +97,7 @@ var cursorActivityDebounce = 50
 var cursorAnimatePeriod = 100
 var supportContainers = ['success', 'info', 'warning', 'danger', 'spoiler']
 var supportCodeModes = ['javascript', 'typescript', 'jsx', 'htmlmixed', 'htmlembedded', 'css', 'xml', 'clike', 'clojure', 'ruby', 'python', 'shell', 'php', 'sql', 'haskell', 'coffeescript', 'yaml', 'pug', 'lua', 'cmake', 'nginx', 'perl', 'sass', 'r', 'dockerfile', 'tiddlywiki', 'mediawiki', 'go', 'gherkin'].concat(hljs.listLanguages())
-var supportCharts = ['sequence', 'flow', 'graphviz', 'mermaid', 'abc']
+var supportCharts = ['sequence', 'flow', 'graphviz', 'mermaid', 'abc', 'plantuml']
 var supportHeaders = [
   {
     text: '# h1',