Update OpenOffice dictionary download link and rephrase dictionary in…

…stallation instructions (closes #3525162)

spellcheck/README

@@ -81,18 +81,21 @@ Configuring dictionaries on Windows
 On Windows, you might need to install the dictionaries (the files
 containing the information for spell checking) manually.
 First, you need to download the dictionary files for the
-languages you want, e.g. from http://wiki.services.openoffice.org/wiki/Dictionaries.
+languages you want, e.g. from
+http://extensions.services.openoffice.org/en/dictionaries.
 Be sure to download the "Spelling" archives from this site. The
 downloaded archive should contain one or more .dic and .aff files.
 
-Once you downloaded the dictionaries, extract them into a folder of
-your choice, e.g. C:\dictionaries. Then open to the Spell Check plugin
-preferences dialog in Geany and choose the folder you just created.
-You may need to restart Geany and then the installed dictionaries should
-be available.
+Instructions::
 
-Currently, installing dictionaries into a custom folder only works
-with Myspell/Hunspell dictionaries (http://hunspell.sourceforge.net/).
+    1. Download the archive you want to use
+    2. The downloaded archive with the extension .oxt is actually a ZIP
+       archive, so extract it as usual (e.g. with 7-Zip or another ZIP
+       unpacker). Extract the contents into a folder of your choice,
+       e.g. C:\dictionaries
+    3. Then open to the Spell Check plugin preferences dialog in Geany and
+       choose the folder you just created. You may need to restart Geany
+       and then the installed dictionaries should be available
 
 
 Known issues