Cleanup (#252)

* Remove empty file 'cd'

Signed-off-by: Gerald Venzl <gerald.venzl@oracle.com>

* Fix small typo/correction in CONTRIBUTING.md

Signed-off-by: Gerald Venzl <gerald.venzl@oracle.com>

* Remove orphaned submodules

Signed-off-by: Gerald Venzl <gerald.venzl@oracle.com>

* Track main branches for submodules

Signed-off-by: Gerald Venzl <gerald.venzl@oracle.com>

---------

Signed-off-by: Gerald Venzl <gerald.venzl@oracle.com>

Author: gvenzl

.gitmodules

@@ -1,15 +1,12 @@
-[submodule "SQL/dw-vldb-samples"]
+[submodule "sql/dw-vldb-samples"]
 	path = sql/dw-vldb-samples
 	url = https://github.com/oracle/dw-vldb-samples
-[submodule "Java/jdbc-ucp"]
-	path = java/jdbc-ucp
-	url = https://github.com/oracle/jdbc-ucp
-[submodule "SQL/analytical-sql-examples"]
-	path = sql/analytical-sql-examples
-	url = https://github.com/oracle/analytical-sql-examples
+	branch = master
 [submodule "db-sample-schemas"]
 	path = db-sample-schemas
 	url = https://github.com/oracle/db-sample-schemas
+	branch = main
 [submodule "dotnet"]
 	path = dotnet
 	url = https://github.com/oracle/dotnet-db-samples
+	branch = master

CONTRIBUTING.md

@@ -1,12 +1,12 @@
 # Contributing to oracle-db-examples
 
-*Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.*
+*Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.*
 
 Pull requests can be made under
 [The Oracle Contributor Agreement](https://www.oracle.com/technetwork/community/oca-486395.html)
 (OCA).
 
-For pull requests to be accepted into oracle-db-examples, the bottom of
+For pull requests to be accepted into this repository, the bottom of
 your commit message must have the following line using your name and
 e-mail address as it appears in the OCA Signatories list.
 
@@ -18,7 +18,7 @@ This can be automatically added to pull requests by committing with:
 
 ```
 git commit --signoff
-````
+```
 
 Only pull requests from committers that can be verified as having
 signed the OCA can be accepted.