Improve key bindings context documentation

[FichteFoll]

Problem description

The documentation regarding available context keys and their relevant values on https://www.sublimemerge.com/docs/key_bindings#context is a bit lacking. Particularly, I was looking for a way to bind a key to the commit tree to copy the commit hash when it has focus.

From the collapse_merge and expand_merge binding, one is able to infer that there is a "commit_table" operand for the "control" key, but the docs are pretty clear here in that only "text_control" is supported.

Preferred solution

Please list all the available operands for the control context key.

Additional Information

The functional key binding is as follows:

  { "keys": ["ctrl+c"],
    "command": "copy_to_clipboard",
    "args": { "text": "$commit" },
    "context": [
        { "key": "control", "operand": "commit_table" },
        { "key": "search_mode", "operator": "not_equal" }
    ]
  },