Fix typos and missing new lines in mail text for admins

[de-jcup]

Current situation

as a new administrator of sechub for environment (base url):https://xx.yy.zz Email adress of new colleague is:xx.xx@example.comDon't forget: Colleague email adress should be added to NPM (email administrators) as well.

Wanted

as a new administrator of sechub for environment (base url):https://xx.yy.zz

Email adress of new colleague is:xx.xx@example.com Don't forget: Colleague email adress should be added to NPM (email administrators) as well.

[de-jcup]

Found another one:

User xxxleft hte group of sechub administrators.

She/He will be no longer admin for environment (base url):https://sechub-xxx.example.com Email adress of old colleague was:xx.yy@example.comDon't forget: Colleague email adress should be removed from NPM (email administrators) as well.

[sven-dmlr]

• tweaked email texts and subjects
• added environment url where possible
• spell corrections
• tested+verified locally

[sven-dmlr]

github actions Go build fails due to #208 Should be gone when PR #209 is merged.

[sven-dmlr]

fixed by https://github.com/Daimler/sechub/pull/245