Doc improvements from LA Clojure Meetup discussion

[seancorfield]

• ~maybe move legacy 1.x stuff to lower down the readme since no one needs to know that now?~
• ~most clauses expect a sequence -- say vector (even tho' it can be a list)~
• ~such as :set -- not immediately obvious there's a connection to update!~
• ~quoted symbolic form -- doesn't work with the ' in the web app~
  • ~it's also not obvious in getting started why this feature exists~
• ~with a parameter of 0 (not clear that this is the result) -- move nil inline ahead?~
• ~inline with single argument -- no, supports multiple elements~
• ~% syntax should use keywords or quoted symbols~
• ~(sql/format {:select [:x [:y :d] [:%z.e] [:%z.f :g]]}) -- don't need [] on %z.e here~
• ~(param x) doesn't work (symbolic form), nor does :params with symbols -- both should~ -- see #543
• ~examples of composite/over -- should have example of/links to other helpers' equivalents~
• ~dialects: mysql stropping isn't readable!~
• ~enable quoting globally via set-dialect! -- example or link!~