add experimental note (#4854)

Author: sdwheeler

reference/7/Microsoft.PowerShell.Core/About/about_If.md

@@ -96,6 +96,10 @@ else {
 
 ### Using the ternary operator syntax
 
+> [!NOTE]
+> This is an experimental feature. For more information see
+> [about_Experimental_Features](about_Experimental_Features.md).
+
 PowerShell 7.0 introduced a new syntax using the ternary operator. It follows the C# ternary
 operator syntax:
 

reference/7/Microsoft.PowerShell.Core/About/about_Operators.md

@@ -444,8 +444,13 @@ $(Get-WmiObject win32_Directory)
 
 #### Ternary operator `? <if-true> : <if-false>`
 
-You can use the ternary operator as a replacement for the `if-else` statement in
-simple conditional cases. The ternary operator was introduced in PowerShell 7.0.
+> [!NOTE]
+> This is an experimental feature. For more information see
+> [about_Experimental_Features](about_Experimental_Features.md).
+
+You can use the ternary operator as a replacement for the `if-else` statement
+in simple conditional cases. The ternary operator was introduced in PowerShell
+7.0 as an experimental feature.
 
 For more information, see [about_If](about_If.md).
 

reference/7/Microsoft.PowerShell.Core/ForEach-Object.md

@@ -73,6 +73,10 @@ Starting in Windows PowerShell 3.0, there are two different ways to construct a
   represent the current input object in the script block. Use the `$using:` keyword to pass variable
   references to the running script.
 
+> [!NOTE]
+> This is an experimental feature. For more information see
+> [about_Experimental_Features](about/about_Experimental_Features.md).
+
 ## EXAMPLES
 
 ### Example 1: Divide integers in an array
@@ -601,7 +605,7 @@ This cmdlet returns objects that are determined by the input.
   block. This is significantly more overhead than running `ForEach-Object` normally with sequential
   processing. It is important to use `-Parallel` where the overhead of running in parallel is small
   compared to work the script block performs. For example:
-  
+
   - Compute intensive scripts on multi-core machines
   - Scripts that spend time waiting for results or doing file operations