doc: mention running gradle check

Signed-off-by: Andreas Reichel <andreas@manticore-projects.com>

Author: manticore-projects

src/site/sphinx/contribution.rst

@@ -61,7 +61,22 @@ The JSQLParser is generated by ``JavaCC`` based on the provided Grammar. The Gra
       * The complete test suite must succeed.
 
    5) Add the description of the new feature to the ``README.md`` file, section `Extensions`.
-   6) Build the package with ``Maven`` and ensure, all checks do pass (PMD and CheckStyle and Code Formatting).
+   6) Build the package with ``Gradle`` and ensure, all checks do pass (PMD and CheckStyle and Code Formatting).
+      .. tab:: Gradle
+
+          .. code-block:: shell
+              :caption: Gradle `check` Task
+
+                  gradle check
+
+      .. tab:: Maven
+
+          .. code-block:: shell
+              :caption: Maven `verify` Task
+
+                  mvn verify
+
+   7) Create your `GitHub Pull Request <https://www.youtube.com/watch?v=nCKdihvneS0>`_
 
 Manage Reserved Keywords
 ------------------------------

src/site/sphinx/unsupported.rst

@@ -5,14 +5,6 @@ Unsupported Grammar of various RDBMS
 *JSQLParser* is a RDBMS agnostic parser with a certain focus on SQL:2016 Standard compliant Queries and the "Big Four" (Oracle, MS SQL Server, Postgres, MySQL/MariaDB).
 We would like to recommend writing portable, standard compliant  SQL in general.
 
-- Postgres Implicit cast is not supported.
-    
-    .. code-block:: java
-
-        SELECT date '2022-12-31';
-        SELECT double precision 1;
-
-
 - Oracle PL/SQL blocks are not support.
 
     .. code-block:: sql
@@ -40,10 +32,6 @@ We would like to recommend writing portable, standard compliant  SQL in general.
 
     While *JSQLParser* provides a lot of generic support for DDL statements, it is possible that certain RDBMS specific syntax (especially about indices, encodings, compression) won't be supported.
 
-- `JSON` or `XML` specific syntax and functions
-
-    While *JSQLParser* provides a lot of generic support for `JSON` or `XML` processing, it is possible that certain RDBMS specific syntax or functions won't be supported.
-
 - Interval Operators
 
     Anything like `DAY HOUR MINUTE SECOND [TO HOUR MINUTE SECOND]` is not supported.: