intro: format link with .Lk

diff --git a/doc/man/man3/intro.3monocypher b/doc/man/man3/intro.3monocypher
index 28bbe4830bfeff72525651a580d3ea43bdf04670..0cf437bbfd40f293dcd73f0151f5e22dd130c8fb 100644 (file)
--- a/doc/man/man3/intro.3monocypher
+++ b/doc/man/man3/intro.3monocypher
@@ -139,7 +139,8 @@ Cryptographic libraries are easy to misuse.
 Even Monocypher allows a number of fatal mistakes.
 .Pp
 Users should follow a formal introduction to cryptography.
-We currently recommend the https://www.crypto101.io/ online course.
+We currently recommend the
+.Lk https://www.crypto101.io/ "Crypto 101 online course" .
 .Ss Random number generation
 Use the facilities of your operating system.
 Avoid user space random number generators.