Update PyThemis installation instructions

content/themis/languages/python/installation.md

@@ -75,13 +75,151 @@ Once PyThemis is installed, you can [try out code examples](../examples/).
 If the stable package version does not suit your needs,
 you can manually build and install the latest version of Themis from source code.
 
+ 1. [Build and install Themis Core library](/themis/installation/installation-from-sources/)
+    into your system.
+
+ 2. Install Python dependencies
+
+    Depending on how you want to install PyThemis, there are different requirements.
+
+    To create a `.whl` package for installation inside virtualenv, you'll need `setuptools` and `wheel`
+
+    * Install globally
+
+      For Debian, Ubuntu:
+
+      ```bash
+      sudo apt install python3-setuptools python3-wheel
+      ```
+
+<!--
+      For CentOS, RHEL:
+
+      ```bash
+      sudo yum install python3-setuptools python3-wheel
+      ```
+-->
+
+    * Or install into virtualenv
+
+      ```bash
+      # activate virtualenv if not done yet
+      pip install setuptools wheel
+      ```
+
+    ---
+
+    To create a system package (i.e. `.deb` one for Debian) you will need `pip` and `fpm`
+
+    * Install globally
+
+      For Debian, Ubuntu:
+
+      ```bash
+      sudo apt install python3-pip lsb-release ruby
+      sudo gem install fpm
+      ```
+
+<!--
+      For CentOS, RHEL:
+
+      ```bash
+      sudo yum install python3-pip ruby
+      sudo gem install fpm
+      ```
+
+    On RHEL you also need to have working `pip` command. If it's not, and you only got `pip3`,
+    create a symlink like this: `sudo ln -s $(which pip3) /usr/bin/pip`.
+-->
+
+ 3. Create a PyThemis package
+
+    * Create a "wheel" for virtualenv
+
+      {{< hint info >}}
+      If you installed dependencies globally, virtualenv should not be activated during wheel
+      generation since needed packages won't be visible in an isolated environment.
+      {{< /hint >}}
+
+      ```bash
+      make pythemis_make_wheel
+      ```
+
+      Result package filename will be printed at the end, like this:
+      ```
+      Result: src/wrappers/themis/python/dist/pythemis-0.14.0-py2.py3-none-any.whl
+      ```
+
+    * Create package for your distro
+
+      For Debian, Ubuntu:
+
+      ```bash
+      make pythemis_deb
+      ```
+
+<!--
+      For CentOS, RHEL:
+
+      ```bash
+      make pythemis_rpm
+      ```
+
+      The result will be located at `build/rpm/python3-pythemis_..._all.rpm`
+      or `build/rpm/python3-pythemis_..._all.rpm` respectively.
+-->
+
+ 4. Install PyThemis
+
+    * Install a wheel into virtualenv
+
+      ```bash
+      # activate virtualenv if not done yet
+      make pythemis_install_wheel
+      ```
+
+      Or manually run `pip install path/to/pythemis-...-none-any.whl` (the package file previously created).
+      If the virtual environment already contained PyThemis of the same version,
+      add `--force-reinstall` option to rewrite the previous package.
+
+    * Install system package
+
+      For Debian, Ubuntu:
+
+      ```bash
+      make pythemis_install_deb
+      ```
+
+      For manual installation, there are two ways:
+      1. `sudo apt install ./path/to/package.deb` (the `./` is important here!)
+      2. `sudo dpkg -i path/to/package.deb`
+
+<!--
+      For CentOS, RHEL:
+
+      ```bash
+      make pythemis_install_rpm
+      ```
+-->
+
+## Building latest version from source (deprecated)
+
+{{< hint warning >}}
+[PEP 668](https://peps.python.org/pep-0668/) changed the way Python packages are managed.
+It is now recommended to use `pip install` to only install packages into isolated virtual environments
+while installing things system-wide should be done using OS package manager (like `apt` or `rpm`).
+This means running `sudo make pythemis_install` is no longer recommended as it copies files
+into system-managed Python directory (like `/usr/lib/python3.X/site-packages`) that is no longer maintained by `pip`.
+Consider building a `.whl` and installing it into your venv instead.
+{{< /hint >}}
+
  1. [Build and install Themis Core library](/themis/installation/installation-from-sources/)
     into your system.
 
  2. Install PyThemis package from the source code:
 
     ```bash
-    make pythemis_install
+    sudo make pythemis_install
     ```
 
     The package will be installed globally into the system.
@@ -91,3 +229,8 @@ you can manually build and install the latest version of Themis from source code
     ```bash
     make prepare_tests_all test_python
     ```
+
+To remove PyThemis after using `pythemis_install`, run
+```bash
+sudo pip uninstall --break-system-packages pythemis
+```