fix typos

README.Rmd

@@ -71,8 +71,8 @@ Cronbach’s alpha | `prec_cronb` | @bonet10
 Sensitivity<sup>1</sup> | `prec_sens` | As per `prec_prop`
 Specificity<sup>1</sup> | `prec_spec` | As per `prec_prop`
 Area under the curve | `prec_auc` | @hm1982
-Negative likelilood ratio<sup>2</sup> | `preg_neg_lr` | @simel1991
-Positive likelilood ratio<sup>2</sup> | `preg_pos_lr` | @simel1991
+Negative likelihood ratio<sup>2</sup> | `prec_neg_lr` | @simel1991
+Positive likelihood ratio<sup>2</sup> | `prec_pos_lr` | @simel1991
 Generic likelilood ratio | `preg_lr` | @simel1991
 
 <sup>1</sup> Simple wrappers for `prec_prop`.