Add CONTRIBUTING.md (#406)

* Add CONTRIBUTING.md

* Include CONTRIBUTING.md in README.md

* Fix broken links

* Update CONTRIBUTING.md

* Update CONTRIBUTING.md

* Use "If a PR" instead of "If the PR"

* Mention fold and pretty printing

* Add missing precedence of the operator '|>'

* Add a note about tests

* Rename to Sophia

* Add missing using keyword

* Update the entire list of keywords in sophia syntax doc

* Add a section about creating a new aesophia release

src/aeso_pretty.erl

@@ -430,6 +430,7 @@ lc_bind(Let) ->
 bin_prec('..')   -> {  0,   0,   0};  %% Always printed inside '[ ]'
 bin_prec('=')    -> {  0,   0,   0};  %% Always printed inside '[ ]'
 bin_prec('@')    -> {  0,   0,   0};  %% Only in error messages
+bin_prec('|>')   -> {150, 150, 200};
 bin_prec('||')   -> {200, 300, 200};
 bin_prec('&&')   -> {300, 400, 300};
 bin_prec('<')    -> {400, 500, 500};