docs: The return value of executable() is a builttarget object.
Make executable() consistent with all other functions returning a
buildtarget, it's return type is a buildtarget object.
@@ -214,7 +214,7 @@ Returns an empty [environment variable object](#environment-object).
### executable()
``` meson
- exe executable(*exe_name*, *sources*, ...)
+ buildtarget executable(*exe_name*, *sources*, ...)
```
Creates a new executable. The first argument specifies its name and the remaining positional arguments define the input files to use. They can be of the following types:
