doc: document add-source --http-header

diff --git a/doc/add-source.rst b/doc/add-source.rst
index 0974731c77e6aab5d87168d6bec0bbf6c2a366d9..22471a894afef6443ed7da2e016bc2791bcaaddf 100644 (file)
--- a/doc/add-source.rst
+++ b/doc/add-source.rst
@@ -18,4 +18,14 @@ URL. It is useful to add a source that is not provided in the index.
 Options
 =======
 
+.. option:: --http-header "Header: Value"
+
+   Add an additional HTTP header to requests for this rule source such
+   as a custom API key. Example::
+
+     add-source --http-header "X-API-Key: 1234"
+
+Common Options
+==============
+
 .. include:: ./common-options.rst