Clarify multiple version requirement behavior (#15979)

Clarify handling of multiple version requirements of disjoint regions

### What does this PR try to resolve?

Resolves a gap in the existing documentation around the dependency
specification for multiple version requirements.

### How to test and review this PR?

As only an update to the cargo book, review should be straightforward

Author: weihanglo

src/doc/src/reference/specifying-dependencies.md

@@ -111,6 +111,8 @@ Here are some examples of comparison requirements:
 
 As shown in the examples above, multiple version requirements can be
 separated with a comma, e.g., `>= 1.2, < 1.5`.
+All requirements must be satisfied,
+so non-overlapping requirements like `<1.2, ^1.2.2` result in no matching versions.
 
 ### Pre-releases