Fix docstring for dbt docs generate

[gnilrets]

Describe the bug

The docstring for dbt docs seems to indicate that if you want to use a different target, you would put the --target parameter before generate:

# dbt docs -h
usage: dbt docs [-h] [--project-dir PROJECT_DIR] [--profiles-dir PROFILES_DIR] [--profile PROFILE] [--target TARGET] [--vars VARS] [--bypass-cache] {generate,serve} ...

However, when I try that, it doesn't honor the parameter

# dbt docs --target prod generate
Running with dbt=0.14.3
Found 125 models, 207 tests, 15 snapshots, 0 analyses, 254 macros, 2 operations, 3 seed files, 101 sources
19:31:38 | Concurrency: 4 threads (target='dev')

However, if I put the flag at the end like this, it works fine:

# dbt docs generate --target prod

Steps To Reproduce

See above

Expected behavior

The docs should be in alignment with the actual commands.

Screenshots and log output

See above

System information

Which database are you using dbt with?

• postgres
• [x ] redshift
• bigquery
• snowflake
• other (specify: ____________)

The output of dbt --version:

installed version: 0.14.3

The operating system you're using: Debian GNU/Linux 10 (buster)

The output of python --version: 3.6.9

Additional context

[drewbanin]

Thanks for the report @gnilrets! I think this should be a quick fix - I just queued this up for our 0.16.0 release. Let me know if it's something you would be interested in contributing a fix for!