Improve 17track action descriptions by using those from the online docs (#138698)

* Improve 17Track action descriptions using those from the online docs

Also change them to third-person singular to match the descriptive style that Home Assistant prefers.

* Add missing period on 2nd description

homeassistant/components/seventeentrack/strings.json

@@ -68,7 +68,7 @@
   "services": {
     "get_packages": {
       "name": "Get packages",
-      "description": "Get packages from 17Track",
+      "description": "Queries the 17track API for the latest package data.",
       "fields": {
         "package_state": {
           "name": "Package states",
@@ -82,7 +82,7 @@
     },
     "archive_package": {
       "name": "Archive package",
-      "description": "Archive a package",
+      "description": "Archives a package using the 17track API.",
       "fields": {
         "package_tracking_number": {
           "name": "Package tracking number",