docs: refactor intro page

Author: mmolari

Diff for: docs/docs/index.md

@@ -10,6 +10,9 @@ Pangraph is currently under heavy development. Bugs and crashes are to be expect
 
 :::
 
+**PanGraph** is a command-line tool for the analysis of bacterial genomes. It compresses multiple genome in a compact **graph representation**, that can be queried to extract information about the evolution of the genomes. It is developed and maintained by [the Neher lab](https://www.biozentrum.unibas.ch/about/administration/administration-a-z/overview/unit/research-group-richard-neher).
+
+## Why Pangraph?
 
 The content and structure of bacterial genomes evolves very rapidly:
 Part of the genome can be cut out, duplicated, or inverted.
@@ -26,6 +29,16 @@ The resultant graph represents contiguous intervals of homologous DNA as vertice
 Edges of the graph are unordered and only exist if at least one genome was found to connect both vertices in either the forward or reverse strand.
 For a more detailed description of the graph structure, see [what is a pangraph](tutorial/t01-building-pangraph.md#what-is-a-pangraph).
 
-This documentation is structures as a [set of tutorials](/category/tutorial) that explain the essential steps to build and manipulate a graph, along with a [reference documentation](/reference) of the available commands. In addition, we provide a python library [pyPanGraph](/category/pypangraph) for analysis of the graph data structure in Python.
+## Documentation outline
+
+This documentation contains: 
+- a [set of tutorials](/category/tutorial) that explain the essential steps to build and manipulate a graph.
+- a [reference documentation](/reference) of the available commands.
+- in addition, we provide a python library [PyPangraph](/category/pypangraph) for analysis of the graph data structure in Python
+
+
+:::info[Legacy Pangraph version]
 
+    This documentation refers to the latest version of pangraph. Code for the previous `v0` version is available on [the `v0` branch](https://github.com/neherlab/pangraph/tree/v0) of the repository, and the legacy documentation is hosted at https://v0.docs.pangraph.org/.
 
+:::