Make arrow annotation arrowhead adjustable (tutorial).

[Only the tutorial patch was kept by the PR committer.]

Author: Abitamim

galleries/users_explain/text/annotations.py

@@ -231,20 +231,20 @@
 # The arguments are the name of the box style with its attributes as
 # keyword arguments. Currently, following box styles are implemented:
 #
-# ==========   ==============   ==========================
+# ==========   ==============   ====================================
 # Class        Name             Attrs
-# ==========   ==============   ==========================
+# ==========   ==============   ====================================
 # Circle       ``circle``       pad=0.3
-# DArrow       ``darrow``       pad=0.3
+# DArrow       ``darrow``       pad=0.3,head_width=1.5,head_angle=90
 # Ellipse      ``ellipse``      pad=0.3
-# LArrow       ``larrow``       pad=0.3
-# RArrow       ``rarrow``       pad=0.3
+# LArrow       ``larrow``       pad=0.3,head_width=1.5,head_angle=90
+# RArrow       ``rarrow``       pad=0.3,head_width=1.5,head_angle=90
 # Round        ``round``        pad=0.3,rounding_size=None
 # Round4       ``round4``       pad=0.3,rounding_size=None
 # Roundtooth   ``roundtooth``   pad=0.3,tooth_size=None
 # Sawtooth     ``sawtooth``     pad=0.3,tooth_size=None
 # Square       ``square``       pad=0.3
-# ==========   ==============   ==========================
+# ==========   ==============   ====================================
 #
 # .. figure:: /gallery/shapes_and_collections/images/sphx_glr_fancybox_demo_001.png
 #    :target: /gallery/shapes_and_collections/fancybox_demo.html