[Flang][OpenMP][Docs] Update target-related support in Flang docs, NFC (#150443)

Update docs to state that reduction is supported on OpenMP `loop` and
`teams` standalone and compound constructs.

(cherry picked from commit 1598062)

Author: skatrak

flang/docs/OpenMPSupport.md

@@ -41,7 +41,7 @@ Note : No distinction is made between the support in Parser/Semantics, MLIR, Low
 | target construct                                           | P      | device clause not supported |
 | target update construct                                    | P      | device clause not supported |
 | declare target directive                                   | P      | |
-| teams construct                                            | P      | reduction clause not supported |
+| teams construct                                            | Y      | |
 | distribute construct                                       | P      | dist_schedule clause not supported |
 | distribute simd construct                                  | P      | dist_schedule and linear clauses are not supported |
 | distribute parallel loop construct                         | P      | dist_schedule clause not supported |
@@ -51,15 +51,15 @@ Note : No distinction is made between the support in Parser/Semantics, MLIR, Low
 | atomic construct extensions                                | Y      | |
 | cancel construct                                           | Y      | |
 | cancellation point construct                               | Y      | |
-| parallel do simd construct                                 | P      | linear clause is not supported |
-| target teams construct                                     | P      | device and reduction clauses are not supported |
-| teams distribute construct                                 | P      | reduction and dist_schedule clauses not supported |
-| teams distribute simd construct                            | P      | reduction, dist_schedule and linear clauses are not supported |
-| target teams distribute construct                          | P      | device, reduction and dist_schedule clauses are not supported |
-| teams distribute parallel loop construct                   | P      | reduction and dist_schedule clauses are not supported |
-| target teams distribute parallel loop construct            | P      | device, reduction and dist_schedule clauses are not supported |
-| teams distribute parallel loop simd construct              | P      | reduction, dist_schedule, and linear clauses are not supported |
-| target teams distribute parallel loop simd construct       | P      | device, reduction, dist_schedule and linear clauses are not supported |
+| parallel do simd construct                                 | P      | linear clause not supported |
+| target teams construct                                     | P      | device clause not supported |
+| teams distribute construct                                 | P      | dist_schedule clause not supported |
+| teams distribute simd construct                            | P      | dist_schedule and linear clauses are not supported |
+| target teams distribute construct                          | P      | device and dist_schedule clauses are not supported |
+| teams distribute parallel loop construct                   | P      | dist_schedule clause not supported |
+| target teams distribute parallel loop construct            | P      | device and dist_schedule clauses are not supported |
+| teams distribute parallel loop simd construct              | P      | dist_schedule and linear clauses are not supported |
+| target teams distribute parallel loop simd construct       | P      | device, dist_schedule and linear clauses are not supported |
 
 ## Extensions
 ### ATOMIC construct