docs(config): fix reference.conf PBFT naming comment

Only committee.pBFTExpireNum has the JavaBean naming mismatch.
Other PBFT keys (PBFTEnable, PBFTPort) start with uppercase
and auto-bind correctly via ConfigBeanFactory.

Author: vividctrlalt

common/src/main/resources/reference.conf

@@ -24,12 +24,12 @@
 #
 # Key naming rules (required for ConfigBeanFactory auto-binding):
 #   - Use standard camelCase: maxConnections, syncFetchBatchNum, etc.
-#   - Do NOT use consecutive uppercase letters at the start: "pBFTExpireNum"
-#     breaks binding because JavaBean spec converts setPBFTExpireNum -> key
-#     "PBFTExpireNum" (capital P), not "pBFTExpireNum" (lowercase p).
-#   - Currently 4 keys violate this rule (all PBFT-related): allowPBFT,
-#     pBFTExpireNum, httpPBFTEnable, httpPBFTPort. These are handled manually
-#     in the bean classes with documented workarounds.
+#   - Keys starting with lowercase then consecutive uppercase break binding:
+#     "pBFTExpireNum" -> setPBFTExpireNum -> property "PBFTExpireNum" (capital P),
+#     mismatches config key "pBFTExpireNum" (lowercase p).
+#   - Only committee.pBFTExpireNum has this issue, handled manually in
+#     CommitteeConfig. Other PBFT keys (PBFTEnable, PBFTPort) start with
+#     uppercase and auto-bind correctly.
 # =============================================================================
 
 net {