spec: remove superfluous terms "delimiter" and "special tokens"

The (original) section on "Operators and Delimiters" introduced
superfluous terminology ("delimiter", "special token") which
didn't matter and was used inconsistently.

Removed any mention of "delimiter" or "special token" and now
simply group the special character tokens into "operators"
(clearly defined via links), and "punctuation" (everything else).

Fixes #19450.

Change-Id: Ife31b24b95167ace096f93ed180b7eae41c66808
Reviewed-on: https://go-review.googlesource.com/38073Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Rob Pike <r@golang.org>

doc/go_spec.html

 <!--{
 	"Title": "The Go Programming Language Specification",
-	"Subtitle": "Version of February 9, 2017",
+	"Subtitle": "Version of February 12, 2017",
 	"Path": "/ref/spec"
 }-->
 
@@ -154,7 +154,7 @@ Any other comment acts like a newline.
 <p>
 Tokens form the vocabulary of the Go language.
 There are four classes: <i>identifiers</i>, <i>keywords</i>, <i>operators
-and delimiters</i>, and <i>literals</i>.  <i>White space</i>, formed from
+and punctuation</i>, and <i>literals</i>.  <i>White space</i>, formed from
 spaces (U+0020), horizontal tabs (U+0009),
 carriage returns (U+000D), and newlines (U+000A),
 is ignored except as it separates tokens
@@ -197,7 +197,7 @@ into the token stream immediately after a line's final token if that token is
 	    <code>return</code>
 	</li>
 
-	<li>one of the <a href="#Operators_and_Delimiters">operators and delimiters</a>
+	<li>one of the <a href="#Operators_and_punctuation">operators and punctuation</a>
 	    <code>++</code>,
 	    <code>--</code>,
 	    <code>)</code>,
@@ -254,10 +254,11 @@ const        fallthrough  if           range        type
 continue     for          import       return       var
 </pre>
 
-<h3 id="Operators_and_Delimiters">Operators and Delimiters</h3>
+<h3 id="Operators_and_punctuation">Operators and punctuation</h3>
 
 <p>
-The following character sequences represent <a href="#Operators">operators</a>, delimiters, and other special tokens:
+The following character sequences represent <a href="#Operators">operators</a>
+(including <a href="#assign_op">assignment operators</a>) and punctuation:
 </p>
 <pre class="grammar">
 +    &amp;     +=    &amp;=     &amp;&amp;    ==    !=    (    )
@@ -4494,8 +4495,8 @@ a[i] = 23
 
 <p>
 An <i>assignment operation</i> <code>x</code> <i>op</i><code>=</code>
-<code>y</code> where <i>op</i> is a binary arithmetic operation is equivalent
-to <code>x</code> <code>=</code> <code>x</code> <i>op</i>
+<code>y</code> where <i>op</i> is a binary <a href="#Arithmetic_operators">arithmetic operator</a>
+is equivalent to <code>x</code> <code>=</code> <code>x</code> <i>op</i>
 <code>(y)</code> but evaluates <code>x</code>
 only once.  The <i>op</i><code>=</code> construct is a single token.
 In assignment operations, both the left- and right-hand expression lists