auto merge of #15166 : zookoatleastauthoritycom/rust/13570-add-see-be…

…low-to-a-reference-to-a-new-concept-2, r=huonw

This is the same patch as submitted to #13570 and #14124, but with @pnkfelix's comment (#14124 (comment)) addressed, and with reflow as a separate commit. I'm submitting it in case @steveklabnik hasn't yet merged a rewrite of the tutorial (#13570 (comment)), in which case this patch might as well be merged into the old tutorial.

src/doc/tutorial.md

@@ -493,11 +493,12 @@ by an *action* (expression). Each case is separated by commas. It is
 often convenient to use a block expression for each case, in which case
 the commas are optional as shown below. Literals are valid patterns and
 match only their own value. A single arm may match multiple different
-patterns by combining them with the pipe operator (`|`), so long as every
-pattern binds the same set of variables. Ranges of numeric literal
-patterns can be expressed with two dots, as in `M..N`. The underscore
-(`_`) is a wildcard pattern that matches any single value. (`..`) is a
-different wildcard that can match one or more fields in an `enum` variant.
+patterns by combining them with the pipe operator (`|`), so long as
+every pattern binds the same set of variables (see "destructuring"
+below). Ranges of numeric literal patterns can be expressed with two
+dots, as in `M..N`. The underscore (`_`) is a wildcard pattern that
+matches any single value. (`..`) is a different wildcard that can match
+one or more fields in an `enum` variant.
 
 ~~~
 # let my_number = 1;