The instruction \centering{\textbf{Description}} creates the error message. Since I can't see a good reason for wanting to center the contents of the header cells, I'd get rid of the \centering directives. (If, for some reason, you simply must center the contents of the right-hand header cell, simply replace \textbf{Description} with \multicolumn{1}{c|}{\textbf{Description}}.
I'd also switch to a tabularx setup and set the target width of the table to \textwidth.
Image may be NSFW.
Clik here to view.
\documentclass{article}\usepackage{tabularx,ragged2e}\usepackage{caption}\begin{document}\begin{table}[htb]\setlength\extrarowheight{2pt} % for a less-cramped look\begin{tabularx}{\textwidth}{ | >{\RaggedRight}p{0.2\linewidth} | % suppress full justification>{\RaggedRight}X | } % suppress full justification\hline\textbf{Feature} & \textbf{Description} \\\hlineCORS control & test \\\hlineRate Limiting & test \\\hline\end{tabularx}\caption{API Gateway Requirements.}\label{tab:api-gateway-requirements}\end{table}\end{document}