docs: Don't use sudo for pip command

sudo is used for global package installations, most libraries
incorporate python packages via local virtual environments. Using sudo
would give chmods the user couldn't access.

If the user needs install globally, they can imply sudo, but even then
it's not advised for python libraries intended to be used
programmatically.

Author: tony

README.md

@@ -13,7 +13,7 @@ python setup.py install
 **install from pip**
 
 ```
-sudo pip install qencode
+pip install --upgrade qencode
 ```
 
 **Usage**

docs/install.md

@@ -13,5 +13,5 @@ python setup.py install
 **install from pip**
 
 ```
-sudo pip install qencode
+pip install --upgrade qencode
 ```

docs/quickstart.md

@@ -13,7 +13,7 @@ python setup.py install
 **install from pip**
 
 ```
-sudo pip install qencode
+pip install --upgrade qencode
 ```
 
 **Usage**