Document plain text soft wrap in default settings (#41456)

Finn Evers created 

Closes #41169

This was alredy present in code before, but not documented in the
default settings, which could lead to confusion,

Release Notes:

- N/A

Change summary

assets/settings/default.json | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

Detailed changes

assets/settings/default.json 🔗 

@@ -1769,7 +1769,8 @@
       }
     },
     "Plain Text": {
-      "allow_rewrap": "anywhere"
+      "allow_rewrap": "anywhere",
+      "soft_wrap": "editor_width"
     },
     "Python": {
       "code_actions_on_format": {