Add edoc generation to CI so that it fails if doc have syntax errors

[michalwski]

This PR fixes edoc errors and adds its verification to CI.

Some time ago @erszcz made an effort to fix our edoc, so that it works for MongooseIM. It's not been checked in our CI, so since then new errors in doc syntax were introduced.

Proposed changes include:

• edoc configuration in rebar.config so that the output is put in edoc directory. The default doc doesn't play nice with our repo since we already have markdown documentation in doc dir.
• edoc generation as part of CI, so that new errors are not introduced
• TODO: fixes to newly added errors

[mongoose-im]

8075.1 / Erlang 22.0 / small_tests / 53ed834
Reports root / small

---

8075.2 / Erlang 22.0 / internal_mnesia / 53ed834
Reports root/ big
OK: 1395 / Failed: 0 / User-skipped: 155 / Auto-skipped: 0

---

8075.4 / Erlang 22.0 / mysql_redis / 53ed834
Reports root/ big
OK: 2625 / Failed: 0 / User-skipped: 205 / Auto-skipped: 0

---

8075.3 / Erlang 22.0 / odbc_mssql_mnesia / 53ed834
Reports root/ big
OK: 2630 / Failed: 0 / User-skipped: 200 / Auto-skipped: 0

---

8075.5 / Erlang 22.0 / riak_mnesia / 53ed834
Reports root/ big
OK: 1528 / Failed: 0 / User-skipped: 162 / Auto-skipped: 0

---

8075.6 / Erlang 22.0 / ldap_mnesia / 53ed834
Reports root/ big
OK: 1359 / Failed: 0 / User-skipped: 191 / Auto-skipped: 0

---

8075.7 / Erlang 22.0 / elasticsearch_and_cassandra_mnesia / 53ed834
Reports root/ big
OK: 328 / Failed: 0 / User-skipped: 28 / Auto-skipped: 0

---

8075.9 / Erlang 21.3 / pgsql_mnesia / 53ed834
Reports root/ big / small
OK: 2643 / Failed: 0 / User-skipped: 187 / Auto-skipped: 0

[mongoose-im]

8076.1 / Erlang 22.0 / small_tests / ab93be9
Reports root / small

---

8076.2 / Erlang 22.0 / internal_mnesia / ab93be9
Reports root/ big
OK: 1395 / Failed: 0 / User-skipped: 155 / Auto-skipped: 0

---

8076.3 / Erlang 22.0 / odbc_mssql_mnesia / ab93be9
Reports root/ big
OK: 2630 / Failed: 0 / User-skipped: 200 / Auto-skipped: 0

---

8076.4 / Erlang 22.0 / mysql_redis / ab93be9
Reports root/ big
OK: 2625 / Failed: 0 / User-skipped: 205 / Auto-skipped: 0

---

8076.7 / Erlang 22.0 / elasticsearch_and_cassandra_mnesia / ab93be9
Reports root/ big
OK: 328 / Failed: 0 / User-skipped: 28 / Auto-skipped: 0

---

8076.5 / Erlang 22.0 / riak_mnesia / ab93be9
Reports root/ big
OK: 1528 / Failed: 0 / User-skipped: 162 / Auto-skipped: 0

---

8076.6 / Erlang 22.0 / ldap_mnesia / ab93be9
Reports root/ big
OK: 1359 / Failed: 0 / User-skipped: 191 / Auto-skipped: 0

---

8076.9 / Erlang 21.3 / pgsql_mnesia / ab93be9
Reports root/ big / small
OK: 2643 / Failed: 0 / User-skipped: 187 / Auto-skipped: 0

[codecov]

Codecov Report

Merging #2695 into master will decrease coverage by 0.42%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2695      +/-   ##
==========================================
- Coverage   79.19%   78.77%   -0.43%     
==========================================
  Files         360      360              
  Lines       30344    30344              
==========================================
- Hits        24030    23902     -128     
- Misses       6314     6442     +128     

Impacted Files	Coverage Δ
src/ejabberd_cowboy.erl	88.78% <ø> (ø)
src/event_pusher/mod_event_pusher_push_plugin.erl	100.00% <ø> (ø)
src/mod_auth_token_rdbms.erl	0.00% <0.00%> (-100.00%)	⬇️
src/inbox/mod_inbox_rdbms_pgsql.erl	0.00% <0.00%> (-100.00%)	⬇️
src/sasl/cyrsasl_oauth.erl	14.28% <0.00%> (-85.72%)	⬇️
src/rdbms/mongoose_rdbms_pgsql_codec_boolean.erl	0.00% <0.00%> (-77.78%)	⬇️
src/rdbms/mongoose_rdbms_pgsql.erl	32.35% <0.00%> (-61.77%)	⬇️
src/mod_auth_token.erl	62.58% <0.00%> (-21.59%)	⬇️
src/elasticsearch/mongoose_elasticsearch.erl	76.92% <0.00%> (-7.70%)	⬇️
src/mongoose_lib.erl	78.57% <0.00%> (-7.15%)	⬇️
... and 26 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6057702...667a784. Read the comment docs.

[NelsonVides]

I think it would be cool to have dialyzer and edoc as two separate jobs on CircleCI, as we have unlimited parallelism already, instead of mixing them, but on the other hand in Travis we don't have such unlimited parallelism. So maybe as two different steps of the same job, so that in Travis they run one after the other and in CircleCi they run at least in separate steps. It's just better organised, but I don't really have a strong opinion there 🤔

[michalwski]

Yeah, I wanted to do it as 2 different steps. It's easy to do on CirlceCI, not that easy (I didn't find a quick solution) with travis considering how our tests are started now.

[gustawlippa]

We sometimes loose knowledge, or even work done for MongooseIM 😢 This PR got lost this way, and this was done in #3333 actually.