Rephrase system-wide vs user-specific bash completion file dir note

It's not that much about whether a command is system-wide or
user-specific, but more about whether the completion is.

In particular, the user-specific completions file dir is used to
override system-wide completion, or to add completion for a command that
does not have a system-wide completion installed. This is orthogonal to
whether the command is installed system-wide or user-specific.

Author: scop

src/cli/help.rs

@@ -169,10 +169,9 @@ pub(crate) static COMPLETIONS_HELP: &str = r"Discussion:
 
     Bash:
 
-    Completion files are commonly stored in
-    `/usr/share/bash-completion/completions` for
-    system-wide commands, but can be stored in
-    `~/.local/share/bash-completion/completions` for user-specific commands.
+    System wide completion files are commonly stored in
+    `/usr/share/bash-completion/completions`, and user-specific ones
+    can be stored in `~/.local/share/bash-completion/completions`.
     Run the command:
 
         $ mkdir -p ~/.local/share/bash-completion/completions

tests/suite/cli-ui/rustup/rustup_completions_cmd_help_flag_stdout.toml

@@ -26,10 +26,9 @@ Discussion:
 
     Bash:
 
-    Completion files are commonly stored in
-    `/usr/share/bash-completion/completions` for
-    system-wide commands, but can be stored in
-    `~/.local/share/bash-completion/completions` for user-specific commands.
+    System wide completion files are commonly stored in
+    `/usr/share/bash-completion/completions`, and user-specific ones
+    can be stored in `~/.local/share/bash-completion/completions`.
     Run the command:
 
         $ mkdir -p ~/.local/share/bash-completion/completions