Quick conda install instructions in main README

[weiji14]

Description of proposed changes

Add simple PyGMT installation instructions using conda and a link to the full installation documentation page.

Fixes #1662

Reminders

• Run make format and make check to make sure the code follows the style guide.
• Add tests for new features or tests that would have caught the bug that you're fixing.
• Add new public functions/methods/classes to doc/api/index.rst.
• Write detailed docstrings for all functions/methods.
• If wrapping a new module, open a 'Wrap new GMT module' issue and submit reasonably-sized PRs.
• If adding new functionality, add an example to docstrings or tutorials.

Slash Commands

You can write slash commands (/command) in the first line of a comment to perform
specific operations. Supported slash commands are:

• /format: automatically format and lint the code
• /test-gmt-dev: run full tests on the latest GMT development version

[weiji14]

Question: Is it better to have conda create ... here (which also creates a new virtual environment), or just use conda install instead?

[maxrjones]

I think for the quickest install instructions we could use conda install to avoid confusion about needing to activate the virtual environment.

[maxrjones]

Thanks for addressing this! I'm fine with the current version, but we could also consolidate the two section headers because there are no other sections under quickstart.

[maxrjones]

Suggested change

	Quickstart
	----------
	Installation
	++++++++++++
	Installation
	------------

[weiji14]

Good catch. I've put in two separate section headers because I'm thinking of adding a small code snippet below the installation as suggested in pyOpenSci/software-submission#43 (comment)

• Vignette(s) demonstrating major functionality that runs successfully locally

Not provided in a textual form but linked as a tutorial video, so for me, it's ok. However, I think that the short copy & paste example below the clip could be applicable for more advanced users who would like to test the package quickly. For example, it could look like:

* Youtube lecture,

* Short installation,

* Copy/Paste example.

[maxrjones]

Sounds good, nice planning 😄

[willschlitzer]

Good addition; I would prefer if the installation instructions were at the top of the page, above the "Why PyGMT" section, but I don't think it is inconveniently far down the home page.