Fixed more typos in the appendix

paper/code-tweetnacl.tex

@@ -10,7 +10,7 @@
 
 \lstinputlisting[language=diff]{tweetnacl.diff}
 
-As follow, we provide the explanations of the above changes to TweetNaCl's code.
+In the following, we provide the explanations of the above changes to TweetNaCl's code.
 
 \begin{itemize}
   \item lines 7-8: We tell VST that \TNaCle{long long} are

paper/proofs.tex

@@ -2,10 +2,10 @@
 \label{appendix:proof-folders}
 
 \subheading{Requirements.}
-Our proofs requires the use of \emph{Coq 8.8.2} for the proofs and
-\emph{Opam 2.0} to manage the dependencies. We are aware that there exists more
-recent versions of Coq; VST; CompCert etc. however to avoid dealing with backward
-breaking compatibility we decided to freeze our dependencies.
+Our proofs require the use of \emph{Coq 8.8.2} and
+\emph{Opam 2.0} to manage the dependencies. We are aware that there exist more
+recent versions of Coq; VST; CompCert etc. However, to avoid dealing with backward
+compatibility issues, we decided to freeze our dependencies.
 
 \subheading{Associated files.}
 The repository containing the proof is composed of two folders \textbf{\texttt{packages}}