docs: SC/21---Insert missing hyphens.

(cherry picked from commit 9261bee)

docs/sc/021/sc21.tex

@@ -720,14 +720,14 @@ \subsection{\xlabel{obs_modes}Observing modes}
 is recommended a minimum of 3, but preferably more than 5,
 \textsc{pong} maps are included in a single observation with a
 rotation introduced between each one. In this way a circular pattern
-is built up, (see the right hand panel of \cref{Figure}{fig:scan}{graphic below}),
+is built up, (see the right-hand panel of \cref{Figure}{fig:scan}{graphic below}),
 with a diameter equal to your requested map size.
 \vspace{0.2cm}\\
-To recover large scale extended structure you are advised to use
+To recover large-scale extended structure you are advised to use
 larger \textsc{pong} maps which scan at a higher rate. This option is
 in preference to tiling multiple smaller maps. Ultimately it is the
 size of the SCUBA-2 field-of-view that determines the sensitivity to
-large scale structure.
+large-scale structure.
 \end{minipage}
 \\ \\ \\
 \begin{minipage}[t]{0.12\linewidth}