fix signature in rapids_export() docs (#732)

Reading through https://docs.rapids.ai/api/rapids-cmake/stable/command/rapids_export/, I noticed what looks like a typo... argument `COMPONENTS` is repeated in the signature of `rapids_export()`. I think that second one was supposed to be `COMPONENTS_EXPORT_SET`.

This fixes that.

Authors:
  - James Lamb (https://github.com/jameslamb)

Approvers:
  - Vyas Ramasubramani (https://github.com/vyasr)

URL: #732

rapids-cmake/export/export.cmake

@@ -67,7 +67,7 @@ calls to :cmake:command:`find_dependency`, or :cmake:command:`CPMFindPackage`.
     rapids_export(BUILD example
       EXPORT_SET example-targets
       COMPONENTS A B
-      COMPONENTS A-export B-export
+      COMPONENTS_EXPORT_SET A-export B-export
       )
 
   This is needed so that :cmake:command:`rapids_export` can correctly