Corrected Code simplifier documentation

[Marc Mittag]

Dear all,

I just tried to use the code simplifier rules and it turned out, that a
lot of things were either not correctly documented or completely missing
in the documentation.

Therefore I did research that and did correct that part of

https://okapiframework.org/wiki/index.php/Filters

What was wrong was the documentation of usage of DATA, where the
examples stated, that you can simply use a tag name. In reality you have
to use the complete code including opening and closing < > characters,
as you find it in xliff.

Also the documentation said TAGTYPE but instead it has to be TAG_TYPE.

For TYPE it was missing, that you can also use tag names as content, so
in the way it previously was (wrongly) documented as usage for DATA.

Also the usage of ORIGINAL_ID and OUTER_DATA was  completely missing and
also the info, that for ITS you (of course) have to escape xml special
chars.

I hope, it fits now.

If someone could review it and correct it with any remaining errors that
would for sure be good.

best

Marc

[Marc Mittag]

ah, to add: What was also missing and I added is, what ADDABLE,
DELETEABLE and CLONEABLE are actually meant to be used for.

best

Marc