Add README

README.md

+# What is himport
+
+The goal of himport is to import accounting data from Dolibarr into a set of hledger
+files.  Currently supported features are:
+
+- bank accounts
+- supplier bills (buy)
+- customer bills (sell)
+- social entries (taxes)
+- VAT
+
+To assign each entry to a specific account, you should have a proper chart of accounts
+in Dolibarr.  Then the himport configuration maps account numbers from Dolibarr to
+hledger accounts (see below).
+
+# Supported Dolibarr versions
+
+himport should be compatible with all versions of Dolibarr from 4.X to 9.X.
+If you encounter issues with any of these versions, this is a bug and should
+be reported.
 
 # Usage from repository