Rollup merge of rust-lang#28485 - Wallacoloo:clarify-let-lhs, r=alexcrichton

In code like `let x = 5`, I am initially confused as to the meaning of "let doesn't take a name on the left hand side, it actually accepts a pattern." - I interpret that as the pattern being located as: `<pattern> let [...]`.

I think what is meant is that the name/pattern is on the left hand side *of the assignment*, rather than to the left of the *let* statement. This change clarifies that.

Author: steveklabnik

src/doc/trpl/guessing-game.md

@@ -147,7 +147,7 @@ a few tricks up their sleeves.
 
 For example, they’re [immutable][immutable] by default. That’s why our example
 uses `mut`: it makes a binding mutable, rather than immutable. `let` doesn’t
-take a name on the left hand side, it actually accepts a
+take a name on the left hand side of the assignment, it actually accepts a
 ‘[pattern][patterns]’. We’ll use patterns later. It’s easy enough
 to use for now: