Programming Language Official Docs and Update

C/C++

C/C++ Features Updates: CPP Reference

C#

C# Feature Proposal: csharplang
C# New Features: What's new in CSharp
C# Official Blog: DevBlogs

ECMAScript

ES Proposals: tc39/proposal
ES Implementations: proposals.es

F-Sharp(F#)

Comment by: https://dev.to/edelsora
F# Feature Proposal: fsharp
F# Official Blog: DevBlogs

Java 🍵

JEP (Java Enhancement Proposal): Java JEP
Java Version "X" Features: JDK Projects
JVM and JEP "X" Comparisons: Chris Who Code
Java Weekly Reading: Baeldung Weekly Review

PHP

PHP Request For Comments: PHP-RFC
PHP RFC Implemented: RFC-IMPL

... more to come
Comments down below if you know similar website for other programming languages