Update information in advocacy section

[carlavilla]

Summary

Updated information in advocacy section:

• Change the incorrect characters `` to ''

• Correct the URL that refers to the Handbook.

• Change the URL of the *BSD conferentes to use https

• Update the number of FreeBSD and OpenBSD ports

• Some corrections with igor

Test Plan

Compile the website.

[bcr]

That's a good change, go ahead with it. Thanks!