binman: Allow creation of entry documentation

Binman supports quite a number of different entries now. The operation of
these is not always obvious but at present the source code is the only
reference for understanding how an entry works.

Add a way to create documentation (from the source code) which can be put
in a new 'README.entries' file.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/binman/control.py

@@ -92,6 +92,10 @@ def SetEntryArgs(args):
 def GetEntryArg(name):
     return entry_args.get(name)
 
+def WriteEntryDocs(modules, test_missing=None):
+    from entry import Entry
+    Entry.WriteDocs(modules, test_missing)
+
 def Binman(options, args):
     """The main control code for binman