Fix spacing in docs for tarfile (GH-20629)

Fix spacing in docs for tarfile (GH-20629)

Before
```
content.txt is 42 bytes in size and isa regular file.
folder is 420 bytes in size and isa directory.
magic is 4200 bytes in size and issomething else.
```

After:
```
content.txt is 42 bytes in size and is a regular file.
folder is 420 bytes in size and is a directory.
magic is 4200 bytes in size and is something else.
```

Automerge-Triggered-By: @orsenthil
(cherry picked from commit 7a280197f4162e5fcdde6f34701a9fa6e669190d)

Co-authored-by: Harsha Laxman <HarshaLaxman@users.noreply.github.com>