docs: update the "how to release" markdown file away from its rst origins

Mainly fixing the link in the first paragraph, but for good measure do
the other conversion pieces and some linter-highlighted best practices:

* number of backticks adjusted for code formatting in md
* unordered list leading space removed
* code block syntax type added

Author: imrehg

docs/how-to-release.md

@@ -1,25 +1,25 @@
 
 # How to release dash-bootstrap-components
 
-This is a set of instructions for releasing to Pypi. The release process is somewhat automated with an `invoke <http://docs.pyinvoke.org/en/latest/getting_started.html>`_ task file. You will need `invoke` and `semver` installed.
+This is a set of instructions for releasing to Pypi. The release process is somewhat automated with an [`invoke`](http://docs.pyinvoke.org/en/latest/getting_started.html>) task file. You will need `invoke` and `semver` installed.
 
- - Run ``invoke prerelease <version>``, where ``version`` is the version number of the release candidate. If you are aiming to release version ``0.0.7``, this will be ``0.0.7-rc1``. This will automatically bump the version numbers and upload the release to Pypi.
+- Run `invoke prerelease <version>`, where `version` is the version number of the release candidate. If you are aiming to release version `0.0.7`, this will be `0.0.7-rc1`. This will automatically bump the version numbers and upload the release to Pypi.
 
- - Verify that you can install the new version and that it works correctly with ``pip install dash-bootstrap-components==<new version>``. It's best to verify the installation on a clean virtual machine (rather than just in a new environment) since installation is more complex than for pure Python packages.
+- Verify that you can install the new version and that it works correctly with `pip install dash-bootstrap-components==<new version>`. It's best to verify the installation on a clean virtual machine (rather than just in a new environment) since installation is more complex than for pure Python packages.
 
- - If the manual installation tests failed, fix the issue and repeat the previous steps with ``rc2`` etc. If installing worked, proceed to the next steps.
+- If the manual installation tests failed, fix the issue and repeat the previous steps with `rc2` etc. If installing worked, proceed to the next steps.
 
- - Run ``invoke release <version>``, where ``version`` is the version number of the release (e.g. ``0.7.0``). You will be prompted to enter a changelog. This will create a release, push it to Pypi and add a tag on current master.
+- Run `invoke release <version>`, where `version` is the version number of the release (e.g. `0.7.0`). You will be prompted to enter a changelog. This will create a release, push it to Pypi and add a tag on current master.
 
- - Verify that the new version is available by running ``pip install dash-bootstrap-components`` in a new virtual environment.
+- Verify that the new version is available by running `pip install dash-bootstrap-components` in a new virtual environment.
 
- - Run ``invoke postrelease <version>``, where ``version`` is the version number of the new release. This will change the version numbers back to a `-dev` version.
+- Run `invoke postrelease <version>`, where `version` is the version number of the new release. This will change the version numbers back to a `-dev` version.
 
 # Releasing documentation changes
 
 The documentation is currently hosted on Heroku. To push documentation updates:
 
-```
+```sh
 git remote add heroku https://git.heroku.com/dash-bootstrap-components.git
 git subtree push --prefix docs/ heroku master
 ```