Update README.md with strike fragment

the strike type fragment was un-documented, so I stuck a mention of it in with the others.

1 files changed, 1 insertions, 0 deletions

diff --git a/README.md b/README.md
index a301d5f..7c6dc93 100644
--- a/README.md
+++ b/README.md
@@ -815,6 +815,7 @@ The default fragment style is to start out invisible and fade in. This style can
 <section>
 	<p class="fragment grow">grow</p>
 	<p class="fragment shrink">shrink</p>
+	<p class="fragment strike">strike</p>
 	<p class="fragment fade-out">fade-out</p>
 	<p class="fragment fade-up">fade-up (also down, left and right!)</p>
 	<p class="fragment fade-in-then-out">fades in, then out when we move to the next step</p>