Context: How to place a table always at the bottom of a page?

When you want to show only a short text the easiest solution is to put the text in the footer of the document. You can use the \doif commands to add the text only on the first page.

\setuppapersize [A5]

\startsetups [footerline]
    \simplealignedbox{.6\textwidth}{flushleft}{Version:}
    \simplealignedbox{.4\textwidth}{flushleft}{1.0}
\stopsetups

\setupfootertexts [\doif{\rawcountervalue[realpage]}{1}{\directsetup{footerline}}]

\starttext
\dorecurse{8}{\samplefile{knuth}}
\stoptext

Edit

When you have a title page you can use a makeup environment (standardmakeup or textmakeup) where you can move the table to the bottom of the page by adding \vfill before the table.

\setuppapersize [A5]

\starttext

\starttextmakeup[pagestate=start]

\samplefile{knuth}

\vfill

\startxtable[frame=off]
    \startxrow
        \startxcell[width=.6\textwidth]
            Version:
        \stopxcell
        \startxcell[width=.4\textwidth]
            1.0
        \stopxcell
    \stopxrow
\stopxtable

\stoptextmakeup

\samplefile{knuth}

\stoptext