Add a reference in plot.rst to the CookBook section "Drawing of Vectors" (#8831)

* Add a reference in plot.rst to the CookBook section "Drawing of Vectors"

* Refine explanation of vector classes and modifiers

Corrected sentence structure and improved clarity regarding vector classes and their modifiers.

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Co-authored-by: Remko Scharroo <remko.scharroo@eumetsat.int>

Author: joa-quim

doc/rst/source/explain_symbols.rst_

@@ -269,6 +269,7 @@
         There are three classes of vectors: Cartesian (left), circular (center) and geographic (right).
         While their use is slightly different, they all share common modifiers that affect how
         they are displayed.
+        See also :ref:`Technical reference - Drawing of Vectors<reference/features:The Drawing of Vectors>`.
 
     **-Sm**\ *size*\ [**+**\ *vecmodifiers*]
         **m**\ ath angle arc, optionally with one or two arrow heads [Default is

doc/rst/source/plot.rst

@@ -323,6 +323,7 @@ Optional Arguments
       **b** (beginning) or **e** (end) to add a vector at only one end [Default is shared specs for both end of the line].
       **Note** - Because **+v** may take additional modifiers it must necessarily be given
       at the end of the pen specification. See the `Vector Attributes`_ for more information or such modifiers.
+      See also :ref:`Technical reference - Drawing of Vectors<reference/features:The Drawing of Vectors>`
     - **+z** - If |-Z| is set, assign pen color via **-C**\ *cpt* and the *z*-values obtained
       (same if transparency is set via |-Z|).  Finally, if pen *color* = *auto*\ [*-segment*] or *auto-table* then
       we will cycle through the pen colors implied by :term:`COLOR_SET` and change on a per-segment