AVRO-3193: Add Rust Checks to Readme (apache#1317)

The README has not been updated since the adoption of the Rust
component. Even though the rust checks aren't passing, having them
present will make it clear to people exploring the repo in GitHub that
there is a rust implementation, and provides guidance about what needs
to be addressed.

README.md

@@ -10,6 +10,10 @@
 [![test python][test python img]][test python]
 [![test php][test php img]][test php]
 
+[![rust continuous integration][rust continuous integration img]][rust continuous integration]
+[![rust clippy check][rust clippy check img]][rust clippy check]
+[![rust security audit][rust security audit img]][rust security audit]
+
 [![codeql c#][codeql c# img]][codeql c#]
 [![codeql java][codeql java img]][codeql java]
 [![codeql javascript][codeql javascript img]][codeql javascript]
@@ -39,6 +43,10 @@ To contribute to Avro, please read:
 [test python]:     https://github.com/apache/avro/actions/workflows/test-lang-py.yml
 [test php]:        https://github.com/apache/avro/actions/workflows/test-lang-php.yml
 
+[rust continuous integration]: https://github.com/apache/avro/actions/workflows/test-lang-rust-ci.yml
+[rust clippy check]:           https://github.com/apache/avro/actions/workflows/test-lang-rust-clippy.yml
+[rust security audit]:         https://github.com/apache/avro/actions/workflows/test-lang-rust-audit.yml
+
 [codeql c#]:         https://github.com/apache/avro/actions/workflows/codeql-csharp-analysis.yml
 [codeql java]:       https://github.com/apache/avro/actions/workflows/codeql-java-analysis.yml
 [codeql javascript]: https://github.com/apache/avro/actions/workflows/codeql-js-analysis.yml
@@ -54,6 +62,10 @@ To contribute to Avro, please read:
 [test python img]:     https://github.com/apache/avro/actions/workflows/test-lang-py.yml/badge.svg
 [test php img]:        https://github.com/apache/avro/actions/workflows/test-lang-php.yml/badge.svg
 
+[rust continuous integration img]: https://github.com/apache/avro/actions/workflows/test-lang-rust-ci.yml/badge.svg
+[rust clippy check img]:           https://github.com/apache/avro/actions/workflows/test-lang-rust-clippy.yml/badge.svg
+[rust security audit img]:         https://github.com/apache/avro/actions/workflows/test-lang-rust-audit.yml/badge.svg
+
 [codeql c# img]:         https://github.com/apache/avro/actions/workflows/codeql-csharp-analysis.yml/badge.svg
 [codeql java img]:       https://github.com/apache/avro/actions/workflows/codeql-java-analysis.yml/badge.svg
 [codeql javascript img]: https://github.com/apache/avro/actions/workflows/codeql-js-analysis.yml/badge.svg