[README] Add note about base branch for bugfixes & new features
[README] Add note about base branch for bugfixes & new features

WouterJ/IvoryCKEditorBundle,egeloen/IvoryCKEditorBundle,cordoval/IvoryCKEditorBundle,arosslau/IvoryCKEditorBundle,browserlondon/IvoryCKEditorBundle,cordoval/IvoryCKEditorBundle,gnat42/IvoryCKEditorBundle,egeloen/IvoryCKEditorBundle,egeloen/IvoryCKEditorBundle,browserlondon/IvoryCKEditorBundle,WouterJ/IvoryCKEditorBundle,gnat42/IvoryCKEditorBundle,arosslau/IvoryCKEditorBundle,arosslau/IvoryCKEditorBundle,markusmichel/IvoryCKEditorBundle,cordoval/IvoryCKEditorBundle,browserlondon/IvoryCKEditorBundle,markusmichel/IvoryCKEditorBundle,markusmichel/IvoryCKEditorBundle,markusmichel/IvoryCKEditorBundle,cordoval/IvoryCKEditorBundle,WouterJ/IvoryCKEditorBundle,gnat42/IvoryCKEditorBundle,browserlondon/IvoryCKEditorBundle,egeloen/IvoryCKEditorBundle,WouterJ/IvoryCKEditorBundle,arosslau/IvoryCKEditorBundle,gnat42/IvoryCKEditorBundle