chore: git-ignore SDK docs (#1492)

This change drops the .genignore rule for docs which didn't seem to be
working and instead opts for adding /client/sdk/docs to the .gitignore
file. This can be beneficial because `speakeasy` will still generate
docs that are available to coding agents as context while not adding
noise to source control.
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Author: disintegrator

.gitignore

@@ -10,6 +10,7 @@ junit-report.xml
 !.vscode/extensions.json
 *.code-workspace
 .idea
+/client/sdk/docs
 /server/goa*
 /server/gram
 # Goa generates OpenAPI v2 specs with non-deterministic examples. Nothing consumes them.