docs: add systemd-language-server to implementations

Implementations.md

@@ -12,6 +12,7 @@
 | _Jedi Language Server_   | [Samuel Roeca](https://softwarejourneyman.com/pages/about.html#about) | [jedi-language-server](https://github.com/pappasam/jedi-language-server)   | Python Language Server wrapping [Jedi](https://github.com/davidhalter/jedi)                                                   |
 | _Ruff Language Server_   | [Charlie Marsh](https://github.com/charliermarsh) | [ruff-lsp](https://github.com/charliermarsh/ruff-lsp) | Language Server for Python's [ruff](https://github.com/charliermarsh/ruff) |
 | _Stata Language Server_   | [Hai Bo](https://github.com/HankBO) | [stata-language-server](https://github.com/HankBO/stata-language-server)   | Language Server for [Stata](https://www.stata.com/)  |
+| _Systemd Language Server_  | [Paweł Sacawa](https://github.com/psacawa)                               | [systemd-language-server](https://github.com/psacawa/systemd-language-server) | Systemd Unit File Language Server
 | _VSCode `autopep8` extension_   | [Microsoft](https://github.com/microsoft) | [vscode-autopep8](https://github.com/microsoft/vscode-autopep8) | VSCode extension for Python's [autopep8](https://github.com/hhatto/autopep8) |
 | _VSCode `black` extension_   | [Microsoft](https://github.com/microsoft) | [vscode-black-formatter](https://github.com/microsoft/vscode-black-formatter) | VSCode extension for Python's [black](https://github.com/psf/black) |
 | _VSCode `isort` extension_   | [Microsoft](https://github.com/microsoft) | [vscode-isort](https://github.com/microsoft/vscode-isort) | VSCode extension for Python's [isort](https://pycqa.github.io/isort) |