From 3173b00128f30ddd5c1ad6d6394b1e9da5c5bb49 Mon Sep 17 00:00:00 2001
From: Patrick Mineault <patrick.mineault@gmail.com>
Date: Thu, 14 Oct 2021 19:58:12 -0400
Subject: [PATCH] Add documentation on how to use custom-builder to generate
 epub (#1451)

* Epub docs

* Update main.py
---
 jupyter_book/cli/main.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/jupyter_book/cli/main.py b/jupyter_book/cli/main.py
index e5a8bd72..d8981696 100644
--- a/jupyter_book/cli/main.py
+++ b/jupyter_book/cli/main.py
@@ -120,9 +120,9 @@ BUILDER_OPTS = {
 @click.option(
     "--custom-builder",
     default=None,
-    help="Specify alternative builder name which allows jupyter-book to use a builder"
-    "provided by an external extension. This can only be used when using"
-    "--builder=custom",
+    help="Specify alternative builder provided by Sphinx, including text and epub. "
+    "This can only be used with --builder=custom. Valid options listed at "
+    "https://www.sphinx-doc.org/en/master/man/sphinx-build.html",
 )
 @click.option(
     "-v", "--verbose", count=True, help="increase verbosity (can be repeated)"
-- 
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