I had a look at the HTML page. I haven't tested how RENAME COLUMN actually works, nor have I looked at the code, so please forgive my ignorance. Here are my comments:
1. The documentation says that you can "rename an existing column in an existing table in any schema", but it doesn't say how you can specify the schema. The syntax only says table-Name.column, not [schema-Name.]table-Name.column. Or is the current schema always used?
2. It is not quite clear to me what function this statement has: "RENAME COLUMN EMPLOYEE.MANAGER TO SUPERVISOR". Is it an example of how to use RENAME COLUMN, or is it an example of a statement that causes the error described in the preceding paragraph?
3. In the paragraph with "Note that you can combine these tools to...", the first sentence says "you" and the second says "I". I think it would be better to use "you" in both sentences. I think I also would have dropped "as follows".
4. "to new datatype" should have "data type" in two words, and perhaps "a" or "the" before "new"?
5. Is the following statement correct? "If there is an index defined on the column, the column can be renamed." Should it have been "cannot"?