Updated readme

Added a bit about updating the default error/warning colors if using
this them with PowerShell.

README.md

@@ -17,8 +17,16 @@ Installation
 Import the `.reg` file of choice, e.g. `regedit /s solarized-dark.reg`.
 
 Both files contain the same palettes, the only difference is the default
-foreground and background colors. Therefore you can switch between themes
-on the fly with `color 81` for dark and `color F6` for light.
+foreground and background colors. Therefore you can switch between themes on
+the fly with `color 81` for dark and `color F6` for light.
+
+If you're using these themes with PowerShell (especially the light), I
+recommend updating the default error and warning colors in your profile at
+`~\Documents\WindowsPowerShell\profile.ps1`. Setting the background colors for
+each to "White"/"Black" for light/dark respectively should do the trick, e.g.
+
+    $Host.PrivateData.DebugBackgroundColor = "Black"
+    $Host.PrivateData.ErrorBackgroundColor = "Black"
 
 Screenshots
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