Update README + github actions.

.github/workflows/continuous.yml

@@ -3,11 +3,11 @@ name: Build
 on:
   push:
     branches:
-      - master
+      - main
       - stable
   pull_request:
     branches:
-      - master
+      - main
       - stable
 
 env:

README.md

@@ -1,8 +1,11 @@
 # libigl - A simple C++ geometry processing library
-[![](https://github.com/libigl/libigl/workflows/Build/badge.svg?event=push)](https://github.com/libigl/libigl/actions?query=workflow%3ABuild+branch%3Amaster+event%3Apush)
-[![](https://github.com/libigl/libigl/workflows/Nightly/badge.svg)](https://github.com/libigl/libigl/actions?query=workflow%3ANightly+branch%3Amaster+event%3Aschedule)
+[![](https://github.com/libigl/libigl/workflows/Build/badge.svg?event=push)](https://github.com/libigl/libigl/actions?query=workflow%3ABuild+branch%3Amain+event%3Apush)
+[![](https://github.com/libigl/libigl/workflows/Nightly/badge.svg)](https://github.com/libigl/libigl/actions?query=workflow%3ANightly+branch%3Amain+event%3Aschedule)
 [![](https://anaconda.org/conda-forge/igl/badges/installer/conda.svg)](https://anaconda.org/conda-forge/igl)
 
 ![](https://libigl.github.io/libigl-teaser.png)
 
 Documentation, tutorial, and instructions at <https://libigl.github.io>.
+
+
+💡 **Note**: [v2.3.0](https://github.com/libigl/libigl/releases/tag/v2.3.0) is our last stable release before some planned major reorganization (see #1696 for details). The upcoming reorganization is aimed at facilitating maintenance and packaging of various libigl components. The next release will be a new major version of libigl (3.0.0). Be mindful if you are updating to the latest commit on the `main` branch of libigl.