[docs][mlgo] Fix list formatting (#139922)

Fix after #139205

llvm/docs/MLGO.rst

diff --git a/llvm/docs/MLGO.rst b/llvm/docs/MLGO.rst
index 692c986..7f58559 100644
--- a/llvm/docs/MLGO.rst
+++ b/llvm/docs/MLGO.rst
@@ -61,6 +61,7 @@
 name, scalar type, and shape tuples.
 
 The main types in LLVM are:
+
 - ``MLModelRunner`` - an abstraction for the decision making mechanism
 - ``TensorSpec`` which describes a tensor.