Formalize rule regarding benchmark lifecycle

Address comment mlcommons#171 (comment)

submission_rules.adoc

@@ -779,8 +779,11 @@ Otherwise, the committee will designate an investigator with no conflict of inte
 2. The result-in-question is moved to open for noncompliance with the rules.
 3. The result-in-question is removed due to intentional cheating.
 
+## Benchmark Lifecycle
 
+Developing high-quality benchmarks requires significant effort, computational resources, and commitment. Therefore, each benchmark is expected to remain part of the benchmark suite for a minimum of two years or four submission rounds, whichever comes first.
 
+A benchmark may be considered for early retirement due to reasons such as, but not limited to, low industry adoption. Early retirement requests will be reviewed by the relevant working group, followed by a formal vote to determine the benchmark's status.
 
 ## Appendices