Merge pull request #918 from ChrisHIV/patch-1

Update expressions.qmd

Author: WardBrian

src/reference-manual/expressions.qmd

@@ -648,7 +648,8 @@ converted to one another (e.g., compared with `==`), then
 a ? b : c
 ```
 
-is an expression of the promoted type of `b` and `c`.  The
+is an expression of the promoted type of `b` and `c`.  The result of this
+expression is `b` if condition `a` is true, `c` otherwise.  The
 only promotion allowed in Stan is integer -> real -> complex; e.g. if one
 argument is of type `int` and the other of type `real`, the
 conditional expression as a whole is of type `real`.