Follow on to WFLY-19844 and WFLY-19845 to do a bit more reorganization in https://docs.wildfly.org/33/Developer_Guide.html

Move the Embedded API section before Application Client one so all the 'Jakarta' ones are grouped together.

Converted the shared web session bit into an Undertow Reference with just a single subsection. After all the Jakarta stuff.

Put 'Jakarta' in various section titles.

Remove the empty 'Development Guidelines and Recommended Practices'

s/Reference Guide/Reference/g in section titles

Remove the empty Weblogic and Websphere migration sections