Be explicit with space assignment in documentation

Merge pull request freqtrade#4609 from freqtrade/new_release

New release 2021.3

Merge pull request freqtrade#4434 from freqtrade/new_release

New release 2020.2

Merge pull request freqtrade#4273 from freqtrade/new_release

New release 2021.1

Merge pull request freqtrade#4127 from freqtrade/new_release

New release 2020.12

Merge pull request freqtrade#4004 from freqtrade/new_release

New release 2020.11

Merge pull request freqtrade#3905 from freqtrade/new_release

New release 2020.10

Version bump 2020.9.1

Merge pull request freqtrade#3805 from freqtrade/new_release

New release 2020.9

Merge pull request freqtrade#3731 from freqtrade/release_2020.8

Release 2020.8