manual: Fix links to Parallel & Spawn (#9342)

(cherry picked from commit eb4272ba1c)

doc/lib.rst

@@ -59,7 +59,7 @@ Core
   This module defines compile-time reflection procs for working with types.
 
 * `threadpool <threadpool.html>`_
-  Implements Nim's `spawn <manual.html#spawn>`_.
+  Implements Nim's `spawn <manual.html#parallel-amp-spawn>`_.
 
 * `cpuinfo <cpuinfo.html>`_
   This module implements procs to determine the number of CPUs / cores.

doc/manual.rst

@@ -8005,7 +8005,7 @@ To enable thread support the ``--threads:on`` command line switch needs to
 be used. The ``system`` module then contains several threading primitives.
 See the `threads <threads.html>`_ and `channels <channels.html>`_ modules
 for the low level thread API. There are also high level parallelism constructs
-available. See `spawn <#parallel-spawn>`_ for further details.
+available. See `spawn <#parallel-amp-spawn>`_ for further details.
 
 Nim's memory model for threads is quite different than that of other common
 programming languages (C, Pascal, Java): Each thread has its own (garbage

lib/pure/concurrency/threadpool.nim

@@ -7,7 +7,7 @@
 #    distribution, for details about the copyright.
 #
 
-## Implements Nim's 'spawn'.
+## Implements Nim's `spawn <manual.html#parallel-amp-spawn>`_.
 
 when not compileOption("threads"):
   {.error: "Threadpool requires --threads:on option.".}