IPCC-AR6-SPM material + info on reference regions

<p>### Contents</p> <p>Included material is from sources indicated below.</p> <p>- `spm/` from **[1]**<br> - `reference-regions/` from **[2]** except for `hexagon_grid_locations.csv`<br> - `reference-regions/hexagon_grid_locations.csv` from **[3]**</p> <p>### [1] source of the data in `spm/`</p> <p>```<br> IPCC, 2021: Summary for Policymakers. In: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S. L. Connors, C. P&eacute;an, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M. I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T. K. Maycock, T. Waterfield, O. Yelek&ccedil;i, R. Yu and B. Zhou (eds.)]. Cambridge University Press. In Press.<br> ```</p> <p>```<br> Gillett, N.P.; Malinina, E.; Kaufman, D.; Neukom, R. (2021): Summary for Policymakers of the Working Group I Contribution to the IPCC Sixth Assessment Report - data for Figure SPM.1 (v20210809). NERC EDS Centre for Environmental Data Analysis, 09 August 2021. doi:10.5285/76cad0b4f6f141ada1c44a4ce9e7d4bd. http://dx.doi.org/10.5285/76cad0b4f6f141ada1c44a4ce9e7d4bd<br> ```</p> <p>### [2] source of the data in csv files</p> <p>```<br> Iturbide, Maialen, Fern&aacute;ndez, Jes&uacute;s, Guti&eacute;rrez, Jos&eacute; Manuel, Bedia, Joaqu&iacute;n, Cimadevilla, Ezequiel, D&iacute;ez-Sierra, Javier, Manzanas, Rodrigo, Casanueva, Ana, Ba&ntilde;o-Medina, Jorge, Milovac, Josipa, Herrera, Sixto, Cofi&ntilde;o, Antonio S., San Mart&iacute;n, Daniel, Garc&iacute;a-D&iacute;ez, Markel, Hauser, Mathias, Huard, David, &amp; Yelekci, &Ouml;zge. (2021). Repository supporting the implementation of FAIR principles in the IPCC-WGI Atlas (v2.0-final). Zenodo. https://doi.org/10.5281/zenodo.5171760<br> ```</p> <p>### [3] source of the data in csv files</p> <p>```<br> Gael Forget, Lauren Milechin, &amp; Philippe Roy. (2021). JuliaClimate/GlobalOceanNotebooks: new webpage, docker+sysimage+Pluto, add IPCC+other notebooks, cleanup (v0.3.5). Zenodo. https://doi.org/10.5281/zenodo.5537709<br> ```</p>