Update Set-OMEConfiguration.md

Updates to BackgroundColor parameter description per Issue #1242.

Author: chrisda

exchange/exchange-ps/exchange/encryption-and-certificates/Set-OMEConfiguration.md

@@ -55,10 +55,14 @@ Accept wildcard characters: False
 ### -BackgroundColor
 The BackgroundColor parameter specifies the background color. Valid values are:
 
-- An HTML hexadecimal \(hex triplet\) color code value (for example, #FFFFFF is white).
+- An available HTML hexadecimal \(hex triplet\) color code value \(for example, 0x000000 is white\).
+
+- An available text value \(for example, yellow is 0x00FFFF00\).
 
 - $null \(blank\). This is the default value.
 
+For the list of available hex and text values, see Background colors for Office 365 Message Encryption (https://support.office.com/article/1508cb35-c5ff-4523-b579-947b21d5515f). 
+
 ```yaml
 Type: String
 Parameter Sets: (All)