Doc: Fix a typo in the "Introduction to QDoc" documentation page

Changes `thinks` to `links` in the 4th paragraph of the "Why Standard
Mode Is Slow" section.

Pick-to: 6.2 6.1 5.15
Fixes: QTBUG-95561
Change-Id: If49f2d58341f33adf8cb8504193d7e3cb3896fcc
Reviewed-by: Paul Wicking <paul.wicking@qt.io>

src/qdoc/doc/qdoc-manual-intro.qdoc

@@ -204,7 +204,7 @@
     module's, that module is said to depend on those other Qt modules.
     Hence when QDoc runs the \e {generate phase} for that module, it
     must also load the index files for those modules so it can create
-    those thinks.
+    those links.
 
     Hence, when the Qt build system generates the Qt documentation, it
     first runs QDoc once for each module to perform the \e {prepare