[site] custom_language_support: add link to color_scheme_management
[site] custom_language_support: add link to color_scheme_management

JetBrains/intellij-sdk-docs,JetBrains/intellij-sdk-docs,chashnikov/intellij-sdk-docs,breandan/intellij-sdk-docs,breandan/intellij-sdk-docs,artspb/intellij-sdk-docs,artspb/intellij-sdk-docs,develar/intellij-sdk-docs,chashnikov/intellij-sdk-docs,chashnikov/intellij-sdk-docs,JetBrains/intellij-sdk-docs,develar/intellij-sdk-docs,artspb/intellij-sdk-docs,artspb/intellij-sdk-docs,breandan/intellij-sdk-docs,develar/intellij-sdk-docs,chashnikov/intellij-sdk-docs