Extend sidebar template to support multiple paragraphs

[ivanov-slk]

Hey all :) I am adding a minor change to the Sidebar template. Please let me know how it looks like.

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Summary:

Allow variable number of paragraphs for Sidebar template's cvevent-s while retaining the original formatting exactly.

Changes:

• Command cvevent modified to support 4 arguments (previously 5). The fourth argument is a list of comma-separated strings, e.g. {string 1, string 2, string 3}, which is parsed into the same format as the original; however allowing any number of bullets;
• A new command introduced, cvlist, which takes a list of strings and parses it with the original formatting;
• Some of the vspace-s are modified to exactly match the original formatting;
• main.tex formatted - hopefully it looks ok;
• A typo fixed in CONTRIBUTING.md.

[ivanov-slk]

@jankapunkt , thank you for your comments; I have edited per your advice.

[jankapunkt]

@ivanov-slk thank you looks great. I will merge, please ignore the CI error, it comes from #49