Update README

README.md

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+# xtgeoapp-grd3dmaps
+
+[![tests](https://github.com/equinor/xtgeoapp-grd3dmaps/actions/workflows/test.yml/badge.svg)](https://github.com/equinor/xtgeoapp-grd3dmaps/actions/workflows/test.yml)
+![Python Version](https://img.shields.io/badge/python-3.8%20|%203.9%20|%203.10%20|%203.11-blue.svg)
+[![License: GPL v3](https://img.shields.io/github/license/equinor/subscript)](https://www.gnu.org/licenses/gpl-3.0)
+[![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
+
+Various scripts for generating maps from 3D grid properties.
+
+## Scripts included
+
+| Script                  |     Description     |
+|-------------------------|---------------------|
+| `grid3d_hc_thickness`   | Make Hydrocarbon thickness maps from Eclipse and/or Roff input |
+| `grid3d_average_map`    | Make average maps from a 3D grid parameter, Eclipse or Roff input |
+| `grid3d_aggregate_map`  | Make aggregated maps (min/max/mean/sum) from a 3D grid parameter, Eclipse or Roff input |
+| `grid3d_migration_time` | Make migration time maps aimed at tracking plume migration in CCS applications |
+
+## Features
+
+- From Eclipse files (EGRID, INIT, UNRST) and/or RMS binary ROFF
+  make HCPV thickness maps, or make weighted average maps
+  - No need to invoke RMS
+  - Efficient in FMU work flows
+  - HC thickness maps and average maps for property differences is
+    supported (see examples in YAML config files)
+- Outputs PNG figures and Irap (RMS) binary maps
+- Simple configuration through a YAML file
+- Configuration from YAML can be overriden by command line options
+- From version 1.3, output via `fmu-dataio`_ (to `sumo`_) is supported.
+  See [fmu-dataio](https://github.com/equinor/fmu-dataio/) and
+  [fmu-sumo](https://github.com/equinor/fmu-sumo)