Provide readme to use Camel LSP in Spacevim

[apupier]

https://spacevim.org/quick-start-guide/
https://spacevim.org/layers/language-server-protocol/#install-language-server

for configuration file, I expect something like to be added:

[[layers]]
name = 'lsp'
filetypes = [
  "xml"
]
[layers.override_cmd]
  xml = ["java", "-jar", "/home/apupier/git/camel-language-server/target/camel-lsp-server-1.1.0-SNAPSHOT.jar"]

doesn't work for me.
not sure how to trigger the completion in SpaceVim(which is a generic issue, not specific to Camel)

potential issue/limitations:

• one server instacne epr language
• how to have both [xml|java|groovy|yaml] and Camel at the same time?

[apupier]

note: latest Camel Language Server can be downloaded from https://oss.sonatype.org/content/repositories/snapshots/com/github/camel-tooling/camel-lsp-server/1.1.0-SNAPSHOT/