Include license and notice files in published crates (#520)

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Hi, this symlinks the license and notice files so they're included in
the published crates (related:
delta-io/delta-rs#3009).

```sh
cd kernel
ln -s ../LICENSE .
ln -s ../NOTICE . 

cd ../derive-macros
ln -s ../LICENSE .
ln -s ../NOTICE . 
```

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N/A

Co-authored-by: Zach Schuermann <[email protected]>

derive-macros/LICENSE

@@ -0,0 +1 @@
+../LICENSE

derive-macros/NOTICE

@@ -0,0 +1 @@
+../NOTICE

kernel/LICENSE

@@ -0,0 +1 @@
+../LICENSE

kernel/NOTICE

@@ -0,0 +1 @@
+../NOTICE