doc: edit text for DEP0104

Make the deprecation message a bit clear and concise.

PR-URL: nodejs#20519
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

doc/api/deprecations.md

@@ -949,11 +949,11 @@ methods in particular can be replaced by using [`util.types`][].
 
 Type: Documentation-only (supports [`--pending-deprecation`][])
 
-Currently when assigning a property to [`process.env`][], the assigned value is
-implicitly converted to a string if it is not a string. This behavior is
-deprecated if the assigned value is not a string, boolean, or number. In the
-future, such assignment may result in a thrown error. Please convert the
-property to a string before assigning it to `process.env`.
+When assigning a non-string property to [`process.env`][], the assigned value is
+implicitly converted to a string. This behavior is deprecated if the assigned
+value is not a string, boolean, or number. In the future, such assignment may
+result in a thrown error. Please convert the property to a string before
+assigning it to `process.env`.
 
 <a id="DEP0105"></a>
 ### DEP0105: decipher.finaltol