Suggested manual changes - section 7.2 Special Properties

[Tommy Kelly <tommy.kelly@verilab.com>]

After figuring out, with help on Reddit (ht: Adam), some nuances
affecting timestamps, column
mode, and the Special Properties TIMESTAMP, and TIMESTAMP_IA, I think
the following
modifications to section 7.2 (Special Properties) of the manual would
be worthwhile.

As it stands, the relevant part reads as follows:
'TIMESTAMP'     The first keyword-less timestamp in the entry.
'TIMESTAMP_IA'  The first inactive timestamp in the entry.

Both are slightly incorrect and that can be fixed by changing to the following:
'TIMESTAMP'     The first inactive keyword-less timestamp in the entry.
'TIMESTAMP_IA'  The first inactive keyword-less timestamp in the entry.

In addition, the following three clarifying details would be useful
(the last of them is required)
perhaps as a footnote:

For both TIMESTAMP and TIMESTAMP_IA: the word "first" refers to the
first occurrence in the entry, not the earliest in time; the prefix
'CLOCK:' at the beginning of a clock entry is considered a keyword in
this context; and timestamps inside property drawers are ignored.

regards.

P.S. I'm not familiar enough with the various moving parts to provide
the above as a proper
git patch. However, FWIW, I did the following. I modified a local copy
of org-manual.org and then I ensured that at least a PDF export
(produced using 'C-c C-e l p', but only the section
in question) looked sensible. Then I produced a diff-based patch file.
Here it is, in case its
of any use:

#### START OF PATCHFILE ####
--- work/git/org-mode/doc/org-manual.org        2022-10-06 11:49:32
+++ org-manual-changed.org      2024-01-27 22:44:36
@@ -5353,8 +5353,8 @@
 | =PRIORITY=     | The priority of the entry, a string with a single
letter.      |
 | =SCHEDULED=    | The scheduling timestamp.
            |
 | =TAGS=         | The tags defined directly in the headline.
            |
-| =TIMESTAMP=    | The first keyword-less timestamp in the entry.
            |
-| =TIMESTAMP_IA= | The first inactive timestamp in the entry.
            |
+| =TIMESTAMP=    | The first active keyword-less timestamp in the
entry.[fn::For both TIMESTAMP and TIMESTAMP_IA: the word "first"
refers to the first occurrence in the entry, not the earliest in time;
the prefix 'CLOCK:' at the beginning of a clock entry is considered a
keyword in this context; and timestamps inside property drawers are
ignored.]          |
+| =TIMESTAMP_IA= | The first inactive keyword-less timestamp in the
entry.        |
 | =TODO=         | The TODO keyword of the entry.
            |

  ** Property Searches
#### END OF PATCHFILE ####