docs: Restore indentation in the definitions of SC/21.
docs: Restore vacuumed spaces to align the MAKEMAP output in SC/21.
docs: Correct typos and grammar in SC/21.
docs: Increment versions and change dates to make a start on the new SC/21.
docs: Add more Starlink definitions to SC/21.
docs: Restore more lost indentation in SC/21.
docs: Tidy prologue headings in SC/21.

Why do we have the question mark, and fullstop when it's not a sentence?
docs: Move glossary from the appendix to just after the table of contents in SC/21.
docs: Use S/N instead of SNR in SC/21.
docs: Rework FCF sections in SC/21.

Now using arcsec and beam instead of aperture and peak respectively.
Some parts were produced by Holly before the recent changes to
PICARD SCUBA2_CHECK_RMS and _CALIBRATE_SCUBA2_DATA_, so may need
further revision.
docs: Use correct janksky unit name in SC/21.
docs: Yet more evacuated indentation restored to SC/21.
docs: Add short caption to figures in SC/21.

The short caption is for the list of figures.

Add extra argument for the short caption in the figure macros,
and supply short captions for all the \myfig* figures.
Indent all the caption text for clarity.
docs: Miscellany of typesetting, punctuation, and typos in SC/21.
docs: Remove appendix of MAKEMAP configuration parameters from SC/21.

Only this appendix used the SST definitions, so remove those too.
docs: Add the List of Figures to SC/21.

Also add/correct the short captions for non \myfig* macros, plus
add one missing from a \myfig figure.
docs: Revert to co-add in SC/21.

At Version 1.2 it had been consistently "coadd" but the lady changed
her mind and it's now "co-add".
docs: Rework "Handling raw SCUBA-2 data" section in SC/21.
docs: Rework "Co-adding multiple maps" section of SC/21.
docs: Rework "Examples of Different Reductions" section in SC/21.

This includes a new figure.