Add brief link to Wiki page describing card mappings to switch decks (#…

…647)

README.md

@@ -133,7 +133,7 @@ If you're upgrading from v3.3 or earlier, then you may want to additionally foll
 
 If you've made, or are thinking of making, any changes to your _Ultimate Geography_ deck, check the [_Customising the deck_](#customising-the-deck) section below to see what will happen to them the next time you upgrade, and whether you need to take any steps to preserve them.
 
-### Levelling up from standard to extended
+### Levelling up from standard to extended (or to experimental)
 
 Importing an extended deck on top of a standard deck is tricky and needs care. You may instead consider learning the extended deck from scratch. To do so, either:
 
@@ -146,6 +146,8 @@ If you'd rather keep your progress, proceed as follows:
 1. Instead of a dialog box confirming that the import was successful, you'll see another dialog box titled _Change Note Type_. In the _Cards_ section, set _Change Flag - Country to:_ to "Flag - Country" (instead of "Country - Flag"), and set _Change Map - Country to:_ to "Map - Country" (instead of "Flag - Country").
 1. Check that the other cards and fields map correctly and click on _OK_ to start the import.
 
+The "mappings" for switching from standard to extended, as well as for all currently possible deck type changes are shown in tabular format [here](https://github.com/anki-geo/ultimate-geography/wiki/Switching-deck-type#specific-guides).
+
 ### Major version
 
 Major versions (e.g. `v3.0`) typically indicate that upgrading ["the normal way"](#upgrading) may lead to a significant loss of progress, or to the loss of [some of the customisations](#customising-the-deck) you may have made to the deck that would normally be preserved. This can occur, for instance, when [significant changes](https://github.com/anki-geo/ultimate-geography/releases/tag/v3.0) are made to the structure of the deck.