Swap ɖ/ɗ

The letter ‘Ɗɗ’ currently seems to be used much more widely (counting in
terms of population) than the letter ‘Ɖɖ’. However, the former is
significantly more difficult to type on Conkey than the latter. This
commit fixes this issue by swapping the two.

Documentation.md

@@ -40,7 +40,7 @@ When using key sequences to input letters, one important detail to be aware of i
 To capitalise a letter produced by a key sequence, the Shift key should be held down during the last key in the sequence only.
 For instance, the lowercase letter ‘ƣ’ is produced by the key sequence `G-f g`,
   while the capital letter ‘Ƣ’ is produced by the key sequence `G-f G` (rather than, say, `G-F g` or `G-F G`).
-Similarly, ‘ɗ’ is produced by `G-{ G-d`, while its capitalised counterpart ‘Ɗ’ is produced by `G-{ G-D`.
+Similarly, ‘ɖ’ is produced by `G-{ G-d`, while its capitalised counterpart ‘Ɖ’ is produced by `G-{ G-D`.
 (However, not all letters have an uppercase form; see below for details.)
 
 Note that dead keys only work before a restricted set of keys.
@@ -212,8 +212,8 @@ Hooks are produced via the `G-{` dead key, which can produce the following lette
 |:------|:-------|:-----------|
 | `b`   | ɓ      | ✔          |
 | `c`   | ƈ      | ✔          |
-| `d`   | ɖ      | ✔          |
-| `G-d` | ɗ      | ✔          |
+| `d`   | ɗ      | ✔          |
+| `G-d` | ɖ      | ✔          |
 | `f`   | ƒ      | ✔          |
 | `g`   | ɠ      | ✔          |
 | `h`   | ɦ      | ✔          |