Remove unused icon

Follow-up-to: 32e38644526745e72e8da6e60633309047830ba2
diff --git a/r/org.eclipse.statet.r.doc/icons/loctool/pin.gif b/r/org.eclipse.statet.r.doc/icons/loctool/pin.gif
deleted file mode 100644
index ec50b70..0000000
--- a/r/org.eclipse.statet.r.doc/icons/loctool/pin.gif
+++ /dev/null
Binary files differ