doc: install instruction changes for curl34 and systemd script typo

[bodnaristvan]

No description provided.

[seniorgod]

thanks for adding curl34 lib repo to solve the problem for buster. I have some questions before merging...

1. The repo does not contain release file. So debian buster will not use it by default. How do you handle that?
2. Currently i test on debian buster arm64 on raspi. Do you know if the repo which seems to reflect on ubuntu (which is of course a debian system) work for debian buster arm64?

[seniorgod]

i get that result on raspbian buster armhf:

root@abacus:/etc/apt/sources.list.d# add-apt-repository ppa:xapienz/curl34
Traceback (most recent call last):
File "/usr/bin/add-apt-repository", line 95, in
sp = SoftwareProperties(options=options)
File "/usr/lib/python3/dist-packages/softwareproperties/SoftwareProperties.py", line 109, in init
self.reload_sourceslist()
File "/usr/lib/python3/dist-packages/softwareproperties/SoftwareProperties.py", line 599, in reload_sourceslist
self.distro.get_sources(self.sourceslist)
File "/usr/lib/python3/dist-packages/aptsources/distro.py", line 93, in get_sources
(self.id, self.codename))
aptsources.distro.NoDistroTemplateException: Error: could not find a distribution template for Raspbian/buster
root@abacus:/etc/apt/sources.list.d#