feat: add an "Alternatives" section

proposals/2024-12-14_update-created-timestamps-for-openmetrics-text.md

@@ -52,6 +52,31 @@ As stated above, `_created`  lines can appear anywhere after its associated metr
 
 ## Alternatives
 
+### Do nothing
+
+Continue using the OM text format in its current state and further optimize CPU usage through PRs that build on [github.com/prometheus/prometheus/issues/14823](https://github.com/prometheus/prometheus/issues/14823) . This is desirable if we wish to keep backwards compatibility but we would have to live with an inefficient solution.
+
+### Storing CTs Using a `# HELP`-Like Syntax
+
+In addition to the `TYPE`, `UNIT`, and `HELP` fields, we can introduce a `# CREATED` line for metrics that have an associated creation timestamp (CT). This approach allows us to quickly determine whether a CT exists for a given metric, eliminating the need for a more time-consuming search process. By parsing the `# CREATED` line, we can associate it with a specific hash corresponding to the metric's label set, thereby mapping each CT to the correct metric.
+
+However, this method still involves the overhead of storing the CT until we encounter the relevant metric line. A more efficient solution would be to place the CT inline with the metric itself, streamlining the process and reducing the need for intermediate storage.
+
+Furthermore the `CREATED`  line itself might look somewhat convoluted compared to `TYPE` , `UNIT` , and `HELP`  which are very human readable. This new `CREATED`  line can end up looking something like this:
+
+```
+# HELP foo Counter with and without labels to certify CT is parsed for both cases
+# TYPE foo counter
+# CREATED 1520872607.123; {a="b"} 1520872607.123
+foo_total 17.0 1520879607.789 # {id="counter-test"} 5
+foo_total{a="b"} 17.0 1520879607.789 # {id="counter-test"} 5
+foo_total{le="c"} 21.0
+foo_created{le="c"} 1520872621.123
+foo_total{le="1"} 10.0
+```
+
+When the same MetricFamily has multiple label sets with their own CTs we'd have to cram all the timestamps with the additional labels with a delimiter in between.
+
 ## Action Plan