Improve user-facing strings of Bang & Olufsen integration (#140062)

- fix typo "Setup …" -> "Set up …"
- fix the wrong capitalization of "… all Connected …"
- change all action descriptions to match Home Assistant style
- reword descriptions of `beolink_expand` and `beolink_unexpand` action using different verbs to better explain them

homeassistant/components/bang_olufsen/strings.json

@@ -197,11 +197,11 @@
   "services": {
     "beolink_allstandby": {
       "name": "Beolink all standby",
-      "description": "Set all Connected Beolink devices to standby."
+      "description": "Sets all connected Beolink devices to standby."
     },
     "beolink_expand": {
       "name": "Beolink expand",
-      "description": "Expand current Beolink experience.",
+      "description": "Adds devices to the current Beolink experience.",
       "fields": {
         "all_discovered": {
           "name": "All discovered",
@@ -221,7 +221,7 @@
     },
     "beolink_join": {
       "name": "Beolink join",
-      "description": "Join a Beolink experience.",
+      "description": "Joins a Beolink experience.",
       "fields": {
         "beolink_jid": {
           "name": "Beolink JID",
@@ -241,11 +241,11 @@
     },
     "beolink_leave": {
       "name": "Beolink leave",
-      "description": "Leave a Beolink experience."
+      "description": "Leaves a Beolink experience."
     },
     "beolink_unexpand": {
       "name": "Beolink unexpand",
-      "description": "Unexpand from current Beolink experience.",
+      "description": "Removes devices from the current Beolink experience.",
       "fields": {
         "beolink_jids": {
           "name": "Beolink JIDs",