Update README.md for clarity and consistency; revise app description and installation instructions, replacing pipenv with poetry.

README.md

@@ -1,16 +1,41 @@
 # Thechart
-App to manage my medication and the evolution of effects.
+App to manage medication and see the evolution of its effects.
 
-## Install
+## Installation
+
+### Install dev environment and dependencies
+The Makefile is set to use the fish shell by default, see the section on [`bash/zsh/csh`](#bash/zsh/csh). The environment will be activated as well, therefore the next section can be skiped, and you can jump to [`run the app`](#Run%20the%20app).
 ```shell
-pipenv install
+make install
 ```
-OR
+
+### Activate the environment according to your shell
+
+#### bash/zsh/csh
 ```shell
-pip install -r requirements.txt
+eval $(poetry env activate)
+```
+
+#### fish
+```shell
+eval (poetry env activate)
+```
+or
+```shell
+make shell
+```
+
+## Run the app
+```shell
+make run
 ```
 
 ## Build container image
 ```shell
 make build
 ```
+
+## Run unit tests
+```shell
+make test
+```