make default installation faster (#2)

* remove cohere as default

* refractor dependencies

* use llama-index pdf reader as default (pypdf)

* fix some lazy docstring

* update install scripts

* minor fix

scripts/run_windows.bat

@@ -114,7 +114,7 @@ IF %ERRORLEVEL% == 0  (
     ECHO Dependencies are already installed
 ) ELSE (
     ECHO Install kotaemon's requirements
-    CALL python -m pip install -e "%CD%\libs\kotaemon\.[dev]"
+    CALL python -m pip install -e "%CD%\libs\kotaemon"
 
     ECHO Install ktem's requirements
     CALL python -m pip install -e "%CD%\libs\ktem"