Fix a couple devbox global command examples (#1665)

## Summary

- `exec ...` should be `eval ...`
- `devbox add ripgrep` was missing `global`

Signed-off-by: Adam DiCarlo <[email protected]>

Author: adamdicarlo0

docs/app/docs/cli_reference/devbox_global.md

@@ -2,11 +2,11 @@
 
 Top level command for managing global packages.
 
-You can use `devbox global` to install packages that you want to use across all your local devbox projects. For example -- if you usually use `ripgrep` for searching in all your projects, you can use `devbox add ripgrep` to make it available whenever you start a `devbox shell` without adding it to each project's `devbox.json.` 
+You can use `devbox global` to install packages that you want to use across all your local devbox projects. For example -- if you usually use `ripgrep` for searching in all your projects, you can use `devbox global add ripgrep` to make it available whenever you start a `devbox shell` without adding it to each project's `devbox.json.` 
 
 You can also use Devbox as a global package manager by adding the following line to your shellrc: 
 
-`exec "$(devbox global shellenv)"`
+`eval "$(devbox global shellenv)"`
 
 For more details, see [Use Devbox as your Primary Package Manager](../devbox_global.md).
 
@@ -32,4 +32,4 @@ devbox global <subcommand> [flags]
 
 ## SEE ALSO
 
-* [devbox](devbox.md)	 - Instant, easy, predictable development environments
+* [devbox](devbox.md)	 - Instant, easy, predictable development environments