Document available condition modules, e.g., for taxonomy

@dewpurdy this will be available but will probably be in another module. I will report back here and update the project page.

The way Drupal 8 works is there Condition plugin system. So if I make another module that has a Taxonomy Condition then it will work with this module and others.

Switching this to a documentation task. Suggested addition to the project page:

The following modules provide additional conditions that can be used with Block Visibility Groups:

• Term Condition provides a simple Condition plugin which checks to see if the current node has a specific taxonomy term.
• Token Conditions creates a simple Token matching condition plugin.
• Vocabulary Condition provides a vocabulary visibility condition. See also #2281659: Create a vocabulary condition.

Updating summary.

@nedjo, thanks for providing the wording! I just added ctools and put on the project page.

Marking fixed but if I got something wrong or if others want to add more re-open.

There are a bunch more condition modules. No doubt we should come up with a better place to track them. For now, though, here are the additional ones:

• Block By Date is a group of modules that provide additional visibility conditions for blocks.
• Condition Pack is used to display blocks conditionally by given dates.
• Entity Field Condition provides a condition plugin that checks to see if a particular entity bundle has a field with a specific value.
• Module Conditions provides a condition of a given module being installed.
• Translation Condition allows a block to be conditionally placed based on whether it has a translation in the currently active language.
• UUID Condition provides a condition plugin that detects a current UUID in the page context.

And the Block Scheduler module (https://www.drupal.org/project/block_scheduler).

and and:

• Block Visibility Conditions (aiming to incorporate a bunch)
• HTTP Client Error Status (block visibility based on status code, that is for 403 access denied and 404 not found pages, yes!)

I came across this module: Views Condition - https://www.drupal.org/project/views_condition