[BUGFIX] Fix ExtJS removal documentation files

A couple of syntax errors in the .rst files of the
ExtJS / page tree feature.

Resolves: #83185
Related: #82426
Releases: master
Change-Id: I010dffddbe565de770868e717d75f16828d60b0b
Reviewed-on: https://review.typo3.org/54897


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Tested-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>