chore: remove coverage file auto generator (#2854)

* chore: remove coverage file auto generator

* chore: remove coverage file auto generator

Author: comphead

dev/release/rat_exclude_files.txt

@@ -12,7 +12,6 @@ dev/diffs/iceberg/*.diff
 dev/release/requirements.txt
 dev/release/rat_exclude_files.txt
 docs/comet-*
-docs/spark_builtin_expr_coverage.txt
 docs/source/_static/images/*.svg
 docs/source/_static/images/comet-dataflow.excalidraw
 docs/source/contributor-guide/benchmark-results/**/*.json

docs/source/contributor-guide/adding_a_new_expression.md

@@ -25,7 +25,7 @@ Before you start, have a look through [these slides](https://docs.google.com/pre
 
 ## Finding an Expression to Add
 
-You may have a specific expression in mind that you'd like to add, but if not, you can review the [expression coverage document](https://github.com/apache/datafusion-comet/blob/f08fcadd5fbdb5b04293d33e654f6c16f81b70c4/doc/spark_builtin_expr_coverage.txt) to see which expressions are not yet supported.
+You may have a specific expression in mind that you'd like to add, but if not, you can review the [expression coverage document](https://github.com/apache/datafusion-comet/blob/main/docs/spark_expressions_support.md) to see which expressions are not yet supported.
 
 ## Implementing the Expression