Remove EOL platforms from README (#2849)

buildkite/README.md

diff --git a/buildkite/README.md b/buildkite/README.md
index d7b6538..341564c 100644
--- a/buildkite/README.md
+++ b/buildkite/README.md
@@ -36,7 +36,7 @@
 
 When you click on a pipeline you can see the last few builds of this pipeline. Clicking on a build
 then gives you access to the details of the build. For example, the below image shows a failed build
-step on Ubuntu 16.04.
+step on Ubuntu.
 
 ![failed build step]
 
@@ -93,7 +93,7 @@
 ---
 tasks:
   ubuntu_build_only:
-    platform: ubuntu2004
+    platform: ubuntu2404
     build_targets:
     - "..."
   windows:
@@ -109,7 +109,7 @@
 ```yaml
 ---
 tasks:
-  ubuntu2004:
+  ubuntu2404:
     build_targets:
     - "..."
   windows:
@@ -128,7 +128,7 @@
 ```yaml
 ---
 tasks:
-  ubuntu1804:
+  ubuntu2404:
     environment:
       CC: clang
     build_targets:
@@ -146,7 +146,7 @@
 ```yaml
 ---
 tasks:
-  ubuntu1804:
+  ubuntu2404:
     shell_commands:
     - rm -f obsolete_file
     run_targets:
@@ -167,7 +167,7 @@
 ```yaml
 ---
 tasks:
-  ubuntu2004:
+  ubuntu2404:
     coverage_targets:
     - "..."
 ```
@@ -179,7 +179,7 @@
 ```yaml
 ---
 tasks:
-  ubuntu1804:
+  ubuntu2404:
     build_flags:
     - "--define=ij_product=clion-latest"
     build_targets:
@@ -209,9 +209,9 @@
     - "//tests/..."
 
 tasks:
-  ubuntu1804:
+  ubuntu2404:
     <<: *common_task_config
-  ubuntu2004:
+  ubuntu2204:
     <<: *common_task_config
   windows:
     <<: *common_task_config
@@ -242,7 +242,7 @@
 
 ### Generating semantic information with Kythe
 
-You can use `kythe_ubuntu2004` platform along with some `index_*` fields to create a task that generate semantic information of your code with [Kythe](https://kythe.io/).
+You can use `kythe_ubuntu2404` platform along with some `index_*` fields to create a task that generate semantic information of your code with [Kythe](https://kythe.io/).
 
 The `index_targets` field contains list of targets that should be indexed.
 
@@ -260,7 +260,7 @@
 ```yaml
 ---
 tasks:
-  kythe_ubuntu2004:
+  kythe_ubuntu2404:
     index_targets:
     - "..."
     index_targets_query: "kind(\"java_(binary|import|library|plugin|test|proto_library) rule\", ...)"
@@ -277,7 +277,7 @@
 ```yaml
 ---
 platforms:
-  ubuntu1804:
+  ubuntu2404:
     build_targets:
     - "..."
     test_targets:
@@ -290,7 +290,7 @@
 ---
 tasks:
   arbitrary_id:
-    platform: ubuntu1804
+    platform: ubuntu2404
     build_targets:
     - "..."
     test_targets:
@@ -302,7 +302,7 @@
 ```yaml
 ---
 tasks:
-  ubuntu1804:
+  ubuntu2404:
     build_targets:
     - "..."
     test_targets:
@@ -325,7 +325,7 @@
   macos:
     build_targets:
     - "..."
-  ubuntu1804:
+  ubuntu2404:
     bazel: 0.18.0
     build_targets:
     - "..."
@@ -446,12 +446,12 @@
 tasks:
   production_code:
     name: "My Project"
-    platform: ubuntu1804
+    platform: ubuntu2404
     test_targets:
     - //...
   examples:
     name: Examples
-    platform: ubuntu1804
+    platform: ubuntu2404
     working_directory: examples_dir
     test_targets:
     - //...
@@ -482,7 +482,7 @@
 ```yaml
 ---
 tasks:
-  ubuntu2004:
+  ubuntu2404:
     include_json_profile:
     - build
     - test
@@ -506,7 +506,7 @@
 ---
 matrix:
   bazel_version: ["4.2.2", "5.0.0"]
-  unix_platform: ["rockylinux8", "debian10", "macos", "ubuntu2004"]
+  unix_platform: ["rockylinux8", "debian10", "macos", "ubuntu2404"]
   python: ["python2", "python3"]
   unix_compiler: ["gcc", "clang"]
   win_compiler: ["msvc", "clang"]
@@ -584,7 +584,7 @@
 ```yaml
 ---
 matrix:
-  platform: ["ubuntu2004", "macos", "windows"]
+  platform: ["ubuntu2404", "macos", "windows"]
   compiler: ["gcc", "clang"]
   exclude:
     - platform: "windows"