Better installation documentation

Author: Halbaroth

docs/sphinx_docs/Install/index.md

@@ -1,23 +1,53 @@
 # Installation
 
-## From a package manager
+# Releases
 
-Alt-ergo is available on [opam], the ocaml package manager with the following command :
+## From opam
+The recommended way to install Alt-Ergo releases is via the OCaml package
+manager [opam]. Simply run:
 ```console
 opam install alt-ergo
 ```
+to install Alt-Ergo in the current switch.
 
-This command will install the Alt-ergo library `alt-ergo-lib`, as well as other librairies detailled in [dependencies](#dependencies).
+## From GitHub releases (Linux and macOS)
+For convenience, binary releases for Linux and macOS (amd64 and arm64) of
+Alt-Ergo are provided on the [GitHub release page](https://github.com/OCamlPro/alt-ergo/releases).
+These binary releases are statically linked and very portable.
+They are distributed under the same licensing restrictions as the source code.
 
-Since version 2.6.0, Alt-Ergo is compatible with opam 2.2 installations using both Cygwin and MSYS2 on Windows. To setup opam on Windows, please follow the instructions [here](https://ocamlpro.com/blog/2024_07_01_opam_2_2_0_releases/).
+# Development versions
 
-## From GitHub releases (Linux and macOS)
+## From opam
+In the git directory, run:
+```
+opam install .
+```
+to install `alt-ergo`, `alt-ergo-lib` and all their dependencies in the current
+switch.
 
-For convenience, binary releases for Linux and macOS (amd64 and arm64) of
-Alt-Ergo are provided on the GitHub release page. These binary releases are
-statically linked and very portable. They are distributed under the same
-licensing restrictions as the source code.
+## From dune
+If you prefer install Alt-Ergo binary in a specific prefix directory [DIR], run
+```
+make deps
+make bin
+dune install -p alt-ergo --prefix DIR
+```
+and
+```
+dune uninstall -p alt-ergo --prefix DIR
+```
+For the Alt-Ergo library
 
+```
+make deps
+make lib
+dune install -p alt-ergo-lib --prefix DIR
+```
+and
+```
+dune uninstall -p alt-ergo-lib --prefix DIR
+```
 ## From sources
 
 ### Dependencies