doc/go1.21: clean up remaining TODOs

These sections are now complete, remove remaining TODOs. Several entries
were missing CL numbers.

For #58645

Change-Id: I67489356016013be876c4bd522afb977becf54ac
Reviewed-on: https://go-review.googlesource.com/c/go/+/502696
Run-TryBot: Michael Pratt <mpratt@google.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>

doc/go1.21.html

@@ -150,10 +150,6 @@ Do not send CLs removing the interior tags from such phrases.
   For details about how to try that language change, see <a href="https://go.dev/wiki/LoopvarExperiment">the LoopvarExperiment wiki page</a>.
 </p>
 
-<p>
-  TODO: complete this section
-</p>
-
 <h2 id="tools">Tools</h2>
 <p>
   Go 1.21 adds improved support for backwards compatibility and forwards compatibility
@@ -250,10 +246,6 @@ Do not send CLs removing the interior tags from such phrases.
 
 <h2 id="runtime-changes">Runtime</h2>
 
-<p>
-  TODO: complete this section, or delete if not needed
-</p>
-
 <p><!-- https://go.dev/issue/7181 -->
   When printing very deep stacks, the runtime now prints the first 50
   (innermost) frames followed by the bottom 50 (outermost) frames,
@@ -312,8 +304,10 @@ Do not send CLs removing the interior tags from such phrases.
   such as inlining the callee.
 </p>
 
+<!-- CL 497455 -->
 <p>
-  TODO: complete this section, or delete if not needed
+  Go 1.21 improves build speed by up to 6%, largely thanks to building the
+  compiler itself with PGO.
 </p>
 
 <h2 id="assembler">Assembler</h2>
@@ -333,16 +327,12 @@ Do not send CLs removing the interior tags from such phrases.
 
 <h2 id="linker">Linker</h2>
 
-<p><!-- https://go.dev/issue/57302, CL 461749 -->
+<p><!-- https://go.dev/issue/57302, CL 461749, CL 457455 -->
   On Windows AMD64, the linker (with help from the compiler) now emits
   SEH unwinding data by default, which improves the integration
   of Go applications with Windows debuggers and other tools.
 </p>
 
-<!-- CL 457455 -->
-<p>
-  <!-- cmd/link: generate .xdata PE section -->
-</p>
 <!-- CL 463395, CL 461315 -->
 <p>
   In Go 1.21 the linker (with help from the compiler) is now capable of
@@ -350,9 +340,6 @@ Do not send CLs removing the interior tags from such phrases.
   entries in the variable initializer is sufficiently large, and if the
   initializer expressions are side-effect free.
 </p>
-<p>
-  TODO: complete this section, or delete if not needed
-</p>
 
 <h2 id="library">Core library</h2>
 
@@ -396,7 +383,7 @@ Do not send CLs removing the interior tags from such phrases.
 
 <h3 id="cmp">New cmp package</h3>
 
-<p><!-- https://go.dev/issue/59488, CL 469356 -->
+<p><!-- https://go.dev/issue/59488, CL 496356 -->
   The new <a href="/pkg/cmp/">cmp</a> package defines the type
   constraint <a href="/pkg/cmp/#Ordered"><code>Ordered</code></a> and
   two new generic functions
@@ -415,10 +402,6 @@ Do not send CLs removing the interior tags from such phrases.
   There are also various performance improvements, not enumerated here.
 </p>
 
-<p>
-  TODO: complete this section
-</p>
-
 <dl id="archive/tar"><dt><a href="/pkg/archive/tar/">archive/tar</a></dt>
   <dd>
     <p><!-- https://go.dev/issue/54451, CL 491175 -->
@@ -538,7 +521,7 @@ Do not send CLs removing the interior tags from such phrases.
 
 <dl id="crypto/tls"><dt><a href="/pkg/crypto/tls/">crypto/tls</a></dt>
   <dd>
-    <p><!-- https://go.dev/issue/60105 -->
+    <p><!-- https://go.dev/issue/60105, CL 496818, CL 496820, CL 496822, CL 496821, CL 501675 -->
       Applications can now control the content of session tickets.
       <ul>
         <li>
@@ -580,13 +563,13 @@ Do not send CLs removing the interior tags from such phrases.
       resumed across versions will fall back to full handshakes.
     </p>
 
-    <p><!-- https://go.dev/issue/44886, https://go.dev/issue/60107 -->
+    <p><!-- https://go.dev/issue/44886, https://go.dev/issue/60107, CL 493655, CL 496995 -->
       The new <a href="/pkg/crypto/tls/#QUICConn"><code>QUICConn</code></a> type
       provides support for QUIC implementations. Note that this is not itself
       a QUIC implementation.
     </p>
 
-    <p><!-- https://go.dev/issue/46308 -->
+    <p><!-- https://go.dev/issue/46308, CL 497377 -->
       The new <a href="/pkg/crypto/tls/#VersionName"></code>VersionName</code></a> function
       returns the name for a TLS version number.
     </p>
@@ -1224,6 +1207,7 @@ Do not send CLs removing the interior tags from such phrases.
 <!-- proposals for x repos that don't need to be mentioned here but
      are picked up by the relnote tool. -->
 <!-- https://go.dev/issue/54232 -->
+<!-- https://go.dev/issue/57792 -->
 <!-- https://go.dev/issue/57906 -->
 <!-- https://go.dev/issue/58668 -->
 <!-- https://go.dev/issue/59676 -->