Add space at end of line where there should be one present (#11729)

* Update everything-about-null.md

Add space at end of line

* Clarify null value output in PowerShell

Wrapped output in single quotes because we don't allow trailing spaces in our documents.

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Co-authored-by: Sean Wheeler <[email protected]>

Author: daniel-brandenburg

reference/docs-conceptual/learn/deep-dives/everything-about-null.md

@@ -61,8 +61,8 @@ If you use `$null` in a string, then it's a blank value (or empty string).
 
 ```powershell
 PS> $value = $null
-PS> Write-Output "The value is $value"
-The value is
+PS> Write-Output "'The value is $value'"
+'The value is '
 ```
 
 This is one of the reasons that I like to place brackets around variables when using them in log