Added a file that explains keyboard shortcuts

KEYBOARD.md

@@ -0,0 +1,34 @@
+# Keyboard shortcuts in Skov
+
+Control H       Show help (for the selected word)
+
+Control L       Load vocabularies from the 'work' directory
+Control E       Export vocabularies to the 'work' directory and save the image
+
+Control V       Create a new vocabulary
+Control N       Create a new word
+
+Return          Register the name of a vocabulary, word or cell
+
+Control I       Convert the selected cell to an input cell
+Control G       Convert the selected cell to a get cell
+Control T       Convert the selected cell to a text cell
+Control W       Convert the selected cell to a word cell
+Control S       Convert the selected cell to a set cell
+Control O       Convert the selected cell to an output cell
+
+Control R       Remove the selected vocabulary, word or cell
+
+Shift ↑         Select the word above
+Shift ↓         Select the word below
+
+↑               Select the cell above
+↓               Select the cell below
+→               Select the cell to the right
+←               Select the cell to the left
+
+Option →        Insert a cell to the right
+Option ←        Insert a cell to the left
+Option ↓        Insert a cell below
+
+Option Return   Show result / Show definition