Update install.md (#1043)

Resolve #1014

doc/en/install.md

@@ -1,9 +1,9 @@
 # Installation #
 
-By executing the install script, blade can be installed under ~/bin. Currently, because it is still in the development stage, the change is still relatively fast.
+By executing the install script, blade can be installed under ~/bin.
 It is installed in a soft chain mode. After installation, the original directory that is checked out cannot be deleted.
 Blade uses ninja as the backend, you need to install ninja.
-Blade requires Python 2.7.x and does not support python3 at this time.
+Blade supports both Python 2.7.x and Python 3，and Python 2.7 support will be deprecated in the future.
 
 Install makes it possible to execute directly in any directory