OpenVas-Scanner Adding information on missing package

[Toys0125]

When I went over the documentation, I had the issue of missing Libcurl when trying to build from cmake. According to the online documentation, Ubuntu doesn't have a direct libcurl-dev package, and using libcurl4-openssl-dev fixes the issue.
additional post about Ubuntu 22.04 missing libcurl

What

I'm adding a warning that if libcurl is missing, here's the package if needed. It is also possible to just add the package to the requirements if the repo owner deems it necessary.

Why

It helps users when building, not having to research why libcurl is missing a package for CMake.

[bjoernricks]

Hi, thanks for bringing this up. It seems that libcurl is a dependency that should be installed by default. Therefore we are going to update the docs for installing libcurl.

[cfi-gb]

@bjoernricks @Toys0125 @greenbone/docs-maintainers It looks like this has been already included in #464 (with the libcurl4-gnutls-dev package added / available here https://greenbone.github.io/docs/latest/22.4/source-build/index.html#openvas-scanner) and is thus not required anymore.