Update README.md

Author: mzelinka

README.md

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 # Summary 
-[![stable version](https://img.shields.io/badge/Current%20version-1.2-brightgreen.svg)](https://github.com/mzelinka/cmip56_forcing_feedback_ecs/releases/tag/v1.2)
+[![stable version](https://img.shields.io/badge/Current%20version-1.3-brightgreen.svg)](https://github.com/mzelinka/cmip56_forcing_feedback_ecs/releases/tag/v1.3)
 
 Three tables and a JSON file are provided containing effective climate sensitivity, effective 2xCO<sub>2</sub> radiative forcing, and radiative feedbacks for all CMIP5 and CMIP6 models that have published output from abrupt CO<sub>2</sub> quadrupling experiments. Two tables contain the "flagship" model variants for CMIP5 and CMIP6. These are typically but not always the 'r1i1p1' variant (CMIP5) or the 'r1i1p1f1' variant (CMIP6), and are updated from Tables S1 and S2 in [Zelinka et al. (2020)](https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL085782).  Results from other model variants are contained in the third "non-flagship" table. All models and variants are contained in the single JSON file (see details below).  Also provided is a figure showing Gregory plots for the CMIP6 models. Methdology is described in [Zelinka et al. (2020)](https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL085782), but the CMIP6 results are regularly updated as new models are published.