Revert "tweak doc for axis tooltip"

This reverts commit f3f8c4f.

Author: plainheart

en/option/component/axis-common.md

@@ -1065,7 +1065,7 @@ xAxis: {
 
 {{ use: partial-version(version = '5.6.0') }}
 
-The tooltip configuration for ${componentType}, must enable global [option.tooltip](~tooltip) component.
+The tooltip configuration for ${componentType}, must set [triggerEvent](~${componentType}.triggerEvent) as `true` and enable global [option.tooltip](~tooltip) component.
 
 ##${prefix} show(boolean) = false
 

zh/option/component/axis-common.md

@@ -1059,7 +1059,7 @@ xAxis: {
 
 {{ use: partial-version(version = '5.6.0') }}
 
-坐标轴 tooltip 设置，注意需启用全局 [option.tooltip](~tooltip) 组件。
+坐标轴 tooltip 设置，注意需设置 [triggerEvent](~${componentType}.triggerEvent) 为 `true` 并启用全局 [option.tooltip](~tooltip) 组件。
 
 ##${prefix} show(boolean) = false