Fix typo in description of PSTernaryOperator experimental feature (PowerShell#10586)

Also make it more consistent with others by not ending in a period.

Author: bergmeister

src/System.Management.Automation/engine/ExperimentalFeature/ExperimentalFeature.cs

@@ -114,7 +114,7 @@ static ExperimentalFeature()
                     description: "New parameter set for ForEach-Object to run script blocks in parallel"),
                 new ExperimentalFeature(
                     name: "PSTernaryOperator",
-                    description: "Support the ternary operator in PowerShell langauge.")
+                    description: "Support the ternary operator in PowerShell language")
             };
             EngineExperimentalFeatures = new ReadOnlyCollection<ExperimentalFeature>(engineFeatures);