From 1ee64f4df877114b7c11192af2a842cdbf2b2b04 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kamil=20=C5=9Aliwak?= <kamil.sliwak@codepoets.it>
Date: Thu, 20 May 2021 21:55:19 +0200
Subject: [PATCH] docs/requirements.txt: Add minimum version for Sphinx

---
 docs/requirements.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/docs/requirements.txt b/docs/requirements.txt
index 268c6e161c0c..038c22b7c495 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,3 +1,6 @@
 sphinx_rtd_theme>=0.3.1
 pygments-lexer-solidity>=0.7.0
 sphinx-a4doc>=1.2.1
+
+# Sphinx 2.1.0 is the oldest version that accepts a lexer class in add_lexer()
+sphinx>=2.1.0