chore: remove unused schematics readme (#13604)

* Since we already track all available schematics in the schematics guide, we should remove the outdated `README.md` for the Angular Material schematics.
* Also while being at it, we should remove the readme for the CDK schematics as well because there is no useful information stored within that readme (the source is self-explaining; and documented mostly)

Author: devversion

src/cdk/schematics/BUILD.bazel

@@ -10,7 +10,7 @@ exports_files(["#bazel_workaround.txt"])
 
 filegroup(
   name = "schematics_assets",
-  srcs = glob(["**/files/**/*", "**/*.json"]) + ["README.md"],
+  srcs = glob(["**/files/**/*", "**/*.json"]),
 )
 
 ts_library(

src/cdk/schematics/README.md

@@ -7,7 +7,7 @@ load("//tools:defaults.bzl", "jasmine_node_test")
 
 filegroup(
   name = "schematics_assets",
-  srcs = glob(["**/files/**/*", "**/*.json"]) + ["README.md"],
+  srcs = glob(["**/files/**/*", "**/*.json"]),
 )
 
 ts_library(