chore: update headings (#175)

Author: fangting-alchemy

standard/ERCs/erc-6900.md

@@ -480,15 +480,15 @@ interface IExecutionHookModule is IModule {
 }
 ```
 
-### Expected behavior
-
-#### Validations and their installation /uninstallation
+### Validations and Their Installation/Uninstallation
 
 An account can have more than one validation module/function installed.
 An account can have the same validation module installed more than once.
 The entityId of a validation function installed on an account MUST be unique.
 Validation installation MAY be deferred until a later time, such as upon first use.
 
+#### Installation
+
 During validation installation, the account MUST correctly set flags and other fields based on the incoming data provided by the user.
 
 - the account MUST install all pre validation hooks required by the user and SHOULD call `onInstall` with the user-provided data on the hook module to initialize the states if required by user.
@@ -498,19 +498,23 @@ During validation installation, the account MUST correctly set flags and other f
 - the account SHOULD call `onInstall` on the validation module to initialize the states if required by user.
 - the account MUST emit `ValidationInstalled` as defined in the interface for all installed validations.
 
+#### Uninstallation
+
 During validation uninstallation, the account MUST correctly clear flags and other fields based on the incoming data provided by the user.
 
 - the account MUST clear all flags for the validation function, like `isGlobal`, `isSignatureValidation`, and `isUserOpValidation`.
 - the account MUST remomve all hooks and SHOULD clear hook module states by calling `onUninstall` with the user-provided data for each hook, including both pre validation hooks and permission hooks, if required by user.
 - the account MUST remove all selectors that the validation function can validate.
 - the account MUST emit `ValidationUninstalled` as defined in the interface for all uninstalled validations.
 
-#### Execution and their installation /uninstallation
+### Execution and Their Installation/Uninstallation
 
 An account can install any number of execution functions.
 An execution function selector MUST be unique in the account.
 An execution function selector MUST not conflict with native ERC-4337 and ERC-6900 functions.
 
+#### Installation
+
 During execution installation, the account MUST correctly set flags and other fields based on the incoming data and module manifest provided by the user.
 
 - the account MUST install all execution functions and set flags and fields as specified in the manifest.
@@ -519,6 +523,8 @@ During execution installation, the account MUST correctly set flags and other fi
 - the account SHOULD call `onInstall` on the execution module to initialize the states if required by user.
 - the account MUST emit `ExecutionInstalled` as defined in the interface for all installed executions.
 
+#### Uninstallation
+
 During execution uninstallation, the account MUST correctly clear flags and other fields based on the incoming data and module manifest provided by the user.
 
 - the account MUST remove all execution functions and clear flags and fields as specified in the manifest.
@@ -527,7 +533,7 @@ During execution uninstallation, the account MUST correctly clear flags and othe
 - the account SHOULD call `onUnInstall` on the execution module to initialize the states and track call success if required by user.
 - the account MUST emit `ExecutionUninstalled` as defined in the interface for all uninstalled executions.
 
-#### Hook execution order
+### Hook Execution Order
 
 It is RECOMMENDED that an account implementer runs hooks in first installed first executed order. However, an account MAY implement a different execution order.