docs: add section about mismatch in TS loading the language service
docs: add section about mismatch in TS loading the language service

Adds information about the issue seen in #594 to the README. cc
@ikilinc.

angular/vscode-ng-language-service,angular/vscode-ng-language-service,angular/vscode-ng-language-service,angular/vscode-ng-language-service