Add info in docs about diagnosing Build Analysis failures (#98778)

* Add docs on how to use build analysis check

docs/workflow/ci/failure-analysis.md

@@ -12,6 +12,19 @@
 
 ## Triaging errors seen in CI
 
+## Summary
+
+**Passing Build Analysis is required to merge into the runtime repo**.
+
+To resolve failures, do the following, in order:
+
+1. Fix the problem if your PR is the cause.
+2. For all failures not in the "Known test errors" section, [try to file a Known Build Error issue](#what-to-do-if-you-determine-the-failure-is-unrelated).
+3. If all else fails, perform a [manual bypass](#bypassing-build-analysis).
+
+
+## Details
+
 In case of failure, any PR on the runtime will have a failed GitHub check - PR Build Analysis - which has a summary of all failures, including a list of matching  known issues as well as any regressions introduced to the build or the tests. This tab should be your first stop for analyzing the PR failures.
 
 ![Build analysis check](analysis-check.png)
@@ -95,6 +108,16 @@ After you do this, if the failure is occurring frequently as per the data captur
 
 There are plenty of intermittent failures that won't manifest again on a retry. Therefore these steps should be followed for every iteration of the PR build, e.g. before retrying/rebuilding.
 
+### Bypassing build analysis
+
+To unconditionally bypass the build analysis check (turn it green), you can add a comment to your PR with the following text:
+
+```
+/ba-g <reason>
+```
+
+For more information, see https://github.com/dotnet/arcade/blob/main/Documentation/Projects/Build%20Analysis/EscapeMechanismforBuildAnalysis.md
+
 ### Examples of Build Analysis
 
 #### Good usage examples