[FORMATTING] vale - disambiguation `Che Plugin`

Che Plugin appears to name, depending on context:

1. all kinds of plug-ins. It should become ` {prod-short}

   plug-ins` in the docs

2. a specific type in the plug-ins `metadata.yaml`. It should be `Che Plugin` in the docs (no attribute).

ffloreth did a first pass of substitutions (script in upstream `tools` directory).

Please investigate further:

1. Are the substitutions relevant?
2. Do we need some disambiguation writeup somewhere?