Doc: remove non-standard use of hyphens in doc/api/tls.markdown
Affected core subsystem(s)
Doc, TLS
Description of change
Fixes #5672 (closed). Removes the non-idiomatic usages of the '-' character. I also tidied up some of the phrasing, grammar, typos and punctuation throughout the whole file. If I should have done this in a separate PR, I'm happy to pull them out and leave only the hyphen changes.
Also, there seems to be an inconsistent use of 'can', 'could' and 'may' throughout the document but I decided against changing that as I don't really know what the house style is.