Update CONTRIBUTING.md
Updates package contribution instructions

- Adds instructions to migrate development from master to devel branch
- Adds comments for all but the most basic git commands
- Adds caution reminding developers to be familiar with git and seek help when it breaks
- Tells user to delete custom branch after submission to METADATA is accepted.

Minor structural changes and reorganizations, e.g. base doc page now has link to Chinese Julia manual in Chinese.
Get package developer to move onto new working branch ASAP.
Ensure branch point is from devel
fix manual example of chained comparisons
parse string interpolations as (string ...) so they can be distinguished
from calls. closes #2786
Merge pull request #2790 from jiahao/patch-1

Update CONTRIBUTING.md
Added link to Portuguese translation
Merge pull request #2791 from jiahao/doc-new

Updates package contribution instructions
Slight change to the doc layout
Document ind2sub and sub2ind
Merge pull request #2794 from jtravs/master

DOC: document ind2sub and sub2ind
fix #2796, spurious error from evalfile with trailing whitespace
not a pretty solution, but better than barfing for now.
cosmetic: tersify a few things in base/loading.jl
doc: add separate latex index

Fixes pdf build failure caused by unicode chinese characters.
doc: don't generate python module index
Add a helpful error message for installing ncurses-devel in case
the build fails while building julia-release-readline.

fix #2799
Make the build error messages a little more prominent.
Add suggestions in the build process if openblas build fails.
The correct option is OPENMP_USE_THREAD=0 for disabling threads in OpenMP