Fix an issue where <h2> was not allowed as an HTML element name

Author: octogonz

tsdoc/src/parser/NodeParser.ts

@@ -1813,8 +1813,9 @@ export class NodeParser {
     let done: boolean = false;
     while (!done) {
       switch (tokenReader.peekTokenKind()) {
-        case TokenKind.AsciiWord:
         case TokenKind.Hyphen:
+        case TokenKind.Period:
+        case TokenKind.AsciiWord:
           tokenReader.readToken();
           break;
         default:

tsdoc/src/parser/StringChecks.ts

@@ -9,7 +9,7 @@ export class StringChecks {
 
   // https://www.w3.org/TR/html5/syntax.html#tag-name
   // https://html.spec.whatwg.org/multipage/custom-elements.html#valid-custom-element-name
-  private static readonly _htmlNameRegExp: RegExp = /^[a-z]+(\-[a-z]+)*$/i;
+  private static readonly _htmlNameRegExp: RegExp = /^[a-z][\-.0-9_a-z]*$/i;
 
   // Note: In addition to letters, numbers, underscores, and dollar signs, modern ECMAScript
   // also allows Unicode categories such as letters, combining marks, digits, and connector punctuation.