Simplify deactivation of development environment

Ref. None

Makefile

@@ -254,15 +254,12 @@ printenv_gnat:
 
 # --- Development environment ---
 
-.PHONY: activate deactivate
+.PHONY: activate
 
 activate: $(BIN_DIR)/poetry
 	@echo . $(DEVEL_VENV)/bin/activate
 	@echo PATH=$$PWD/.bin:\$$PATH
 
-deactivate:
-	@echo deactivate
-
 $(BIN_DIR)/poetry:
 	@mkdir -p $(BIN_DIR)
 	@ln -sf $(POETRY) $(BIN_DIR)

doc/development_guide/index.rst

@@ -78,13 +78,13 @@ Poetry will always be installed into its own environment (`.venv.poetry`).
 It is not necessary to explicitly activate the virtual environments before executing any of the `make` targets.
 They are used automatically during the execution of `make`.
 However, in order to have the `rflx` command directly available in the shell, it is necessary to activate the project's virtual environment.
-The following `make` targets can be used to respectively activate and deactivate it, as well as add or remove Poetry to/from the `PATH`.
-Note the need to use `source <(...)` in the commands below.
+The following commands can be used to respectively activate and deactivate it, as well as add or remove Poetry to/from the `PATH`.
+Note the need to use `source <(...)` in the command below.
 
 .. code:: console
 
    $ source <(make activate)
-   $ source <(make deactivate)
+   $ deactivate
 
 Alternatively, RecordFlux can be executed also via Poetry by executing `.venv.poetry/bin/poetry run rflx`.