New features and docs rewrite
[FEATURE] Added PSR-14 events to modify variables for administration module #1149 - thanks @DaRealFreak
[FEATURE] Added ModifyCheckRegistrationSuccessEvent PSR-14 event #1151
[BUGFIX] Exclude disableOverrideDemand in dataHandler hook #1148
[BUGFIX] Show enableInvoice extension setting again
[DOCS] Rework documentation to latest TYPO3 standards #1143
[DOCS] Added backend module template override documentation #1144
[DOCS] Added 2 new PSR-14 events to docs section
[DOCS] Remove eventuid from aspect #1150