Add wording consistency for update/upgrade controversy

Change main command for updating to “update_oh_my_zsh”. Seems to be
more conventional and human-readable. Some internal stuff still keeps
“upgrade”. Needs thorough testing. And maybe a transitional message for
existing users

README.md

@@ -164,13 +164,13 @@ If you would like to override the functionality of a plugin distributed with Oh
 
 ## Getting Updates
 
-By default, you will be prompted to check for upgrades every few weeks. If you would like `oh-my-zsh` to automatically upgrade itself without prompting you, set the following in your `~/.zshrc`:
+By default, you will be prompted to check for updates every few weeks. If you would like `oh-my-zsh` to automatically update itself without prompting you, set the following in your `~/.zshrc`:
 
 ```shell
 DISABLE_UPDATE_PROMPT=true
 ```
 
-To disable automatic upgrades, set the following in your `~/.zshrc`:
+To disable automatic updates, set the following in your `~/.zshrc`:
 
 ```shell
 DISABLE_AUTO_UPDATE=true
@@ -178,10 +178,10 @@ DISABLE_AUTO_UPDATE=true
 
 ### Manual Updates
 
-If you'd like to upgrade at any point in time (maybe someone just released a new plugin and you don't want to wait a week?) you just need to run:
+If you'd like to update at any point in time (maybe someone just released a new plugin and you don't want to wait a week?) you just need to run:
 
 ```shell
-upgrade_oh_my_zsh
+update_oh_my_zsh
 ```
 
 Magic!

lib/functions.zsh

@@ -6,8 +6,8 @@ function uninstall_oh_my_zsh() {
   env ZSH=$ZSH sh $ZSH/tools/uninstall.sh
 }
 
-function upgrade_oh_my_zsh() {
-  env ZSH=$ZSH sh $ZSH/tools/upgrade.sh
+function update_oh_my_zsh() {
+  env ZSH=$ZSH sh $ZSH/tools/update.sh
 }
 
 function take() {

tools/check_for_upgrade.sh

@@ -11,7 +11,7 @@ function _update_zsh_update() {
 }
 
 function _upgrade_zsh() {
-  env ZSH=$ZSH sh $ZSH/tools/upgrade.sh
+  env ZSH=$ZSH sh $ZSH/tools/update.sh
   # update the zsh file
   _update_zsh_update
 }