trailer doc: narrow down scope of --where and related flags

The wording "all configuration variables" is misleading (the same could
be said to the descriptions of the "--[no-]if-exists" and the
"--[no-]if-missing" options).  Specifying --where=value overrides only
the trailer.where variable and applicable trailer.<token>.where
variables, and --no-where stops the overriding of these variables.
Ditto for the other two with their relevant configuration variables.

Reported-by: Junio C Hamano <[email protected]>
Signed-off-by: Linus Arver <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Linus Arver

Documentation/git-interpret-trailers.txt

@@ -112,7 +112,8 @@ OPTIONS
 --where <placement>::
 --no-where::
 	Specify where all new trailers will be added.  A setting
-	provided with '--where' overrides all configuration variables
+	provided with '--where' overrides the `trailer.where` and any
+	applicable `trailer.<token>.where` configuration variables
 	and applies to all '--trailer' options until the next occurrence of
 	'--where' or '--no-where'. Upon encountering '--no-where', clear the
 	effect of any previous use of '--where', such that the relevant configuration
@@ -123,7 +124,8 @@ OPTIONS
 --no-if-exists::
 	Specify what action will be performed when there is already at
 	least one trailer with the same <token> in the input.  A setting
-	provided with '--if-exists' overrides all configuration variables
+	provided with '--if-exists' overrides the `trailer.ifExists` and any
+	applicable `trailer.<token>.ifExists` configuration variables
 	and applies to all '--trailer' options until the next occurrence of
 	'--if-exists' or '--no-if-exists'. Upon encountering '--no-if-exists, clear the
 	effect of any previous use of '--if-exists, such that the relevant configuration
@@ -134,7 +136,8 @@ OPTIONS
 --no-if-missing::
 	Specify what action will be performed when there is no other
 	trailer with the same <token> in the input.  A setting
-	provided with '--if-missing' overrides all configuration variables
+	provided with '--if-missing' overrides the `trailer.ifMissing` and any
+	applicable `trailer.<token>.ifMissing` configuration variables
 	and applies to all '--trailer' options until the next occurrence of
 	'--if-missing' or '--no-if-missing'. Upon encountering '--no-if-missing,
 	clear the effect of any previous use of '--if-missing, such that the relevant