v4.8.3: add release default.xml and changelog.txt

[KanjiMonster]

Set default.xml to fixed revisions based on tonight's nightly, with the following changes:

• bisdn-linux: point to 4.8.3 branch with release FEEDURIPREFIX
• meta-open-network-linux: point to fixes branch for 4.8.3

and add a changelog.txt generated based on these values.

Signed-off-by: Jonas Gorski jonas.gorski@bisdn.de

[hilmarm]

lgtm