Set company-capf as backend for ledger-mode.

This provides pretty, and very useful completion of accounts.
Inspired by the Finance layer for Spacemacs.

Signed-off-by: Johan Thoren <johan@thoren.dev>

modules/lang/ledger/config.el

@@ -12,6 +12,8 @@
             "hledger"
           "ledger"))
 
+  (set-company-backend! 'ledger-mode 'company-capf)
+
   (defadvice! +ledger--check-version-a (orig-fn)
     "Fail gracefully if ledger binary isn't available."
     :around #'ledger-check-version