\documentclass{article}

% Files
\usepackage[subpreambles=true]{standalone}
\usepackage{import}

\usepackage[T1]{fontenc} % encoding
\renewcommand{\familydefault}{\sfdefault} % sans-serif font

% Langages
\usepackage[french]{babel}
\frenchsetup{SmallCapsFigTabCaptions=false}

% Add \extra info to title
\makeatletter
\providecommand{\extra}[1]{
  \apptocmd{\@author}{
    \end{tabular}
    \par\vspace*{0.7em}
    \begin{tabular}[t]{c}
    #1}{}{}
}
\makeatother

% Change page dimensions
% \usepackage[
%   a4paper,
%   left=20mm,
%   top=20mm,
% ]{geometry}

% Bibliography
\bibliographystyle{unsrt}
\nocite{*}

% Metadatas
\def\docTitle{TITLE}
\def\docAuthor{YOU}
\def\authorMail{mailto:place@holder.com}
\def\docSubject{SUBJECT}
\def\docLocation{LOCATION}

% Dependencies
\usepackage[
  pdfauthor={\docAuthor},
  pdftitle={\docTitle},
  pdfsubject={\docSubject}, % subject metadata
  hidelinks,
]{hyperref}


\title{\docTitle}
\author{\docAuthor}
\extra{\docSubject~$\cdot$ \docLocation}
\date{}

\begin{document}
\maketitle
\flushbottom
\tableofcontents
\clearpage

\section{First section}
\import{sections/}{section1}

\section{Second section}
\import{sections/}{section2}

\section{Third section}
\import{sections/}{section3}

\clearpage
\appendix
\bibliography{sources}

\end{document}