Add a reference between the Strings node and Search/Replace

* doc/lispref/strings.texi (Creating Strings): Mention
string-replace/replace-regexp-in-string (bug#45516).

(cherry picked from commit b9359d4183)

doc/lispref/strings.texi

@@ -120,7 +120,10 @@ character (i.e., an integer), @code{nil} otherwise.
 @cindex string creation
 
   The following functions create strings, either from scratch, or by
-putting strings together, or by taking them apart.
+putting strings together, or by taking them apart.  (For functions that
+create strings based on searching the contents of other strings (like
+@code{string-replace} and @code{replace-regexp-in-string}), see
+@ref{Search and Replace}.)
 
 @defun make-string count character &optional multibyte
 This function returns a string made up of @var{count} repetitions of