docs(golang): add mage cross-platform build guide - #304

Changed pages include:

• index.html - view
• 404.html - view
• search.html - view
• zh-hans/index.html - view
• blog/introduction.html - view
• guides/introduction.html - view
• restapi/commonconfigs.html - view
• restapi/commonfields.html - view
• restapi/contentdescription.html - view
• restapi/errcode.html - view

There are more changes not included in the list