docs: add note of dots in database/table/column names

Author: kenjis

user_guide_src/source/database/configuration.rst

@@ -113,6 +113,8 @@ Explanation of Values:
 **username**    The username used to connect to the database.
 **password**    The password used to connect to the database.
 **database**    The name of the database you want to connect to.
+
+                .. note:: CodeIgniter doesn't support dots (``.``) in the database, table, and column names.
 **DBDriver**    The database type. e.g.,: ``MySQLi``, ``Postgres``, etc. The case must match the driver name
 **DBPrefix**    An optional table prefix which will added to the table name when running
                 :doc:`Query Builder <query_builder>` queries. This permits multiple CodeIgniter

user_guide_src/source/database/examples.rst

@@ -6,6 +6,8 @@ The following page contains example code showing how the database class
 is used. For complete details please read the individual pages
 describing each function.
 
+.. note:: CodeIgniter doesn't support dots (``.``) in the database, table, and column names.
+
 .. contents::
     :local:
     :depth: 2

user_guide_src/source/database/queries.rst

@@ -10,6 +10,8 @@ Queries
 Query Basics
 ************
 
+.. note:: CodeIgniter doesn't support dots (``.``) in the database, table, and column names.
+
 Regular Queries
 ===============
 

user_guide_src/source/database/query_builder.rst

@@ -15,6 +15,8 @@ the query syntax is generated by each database adapter. It also allows
 for safer queries, since the values are escaped automatically by the
 system.
 
+.. note:: CodeIgniter doesn't support dots (``.``) in the database, table, and column names.
+
 .. contents::
     :local:
     :depth: 2