Lots of broken links in "Create Your Own Colormap" page

[jypeter]

@lee1043 @doutriaux1 There are lots of broken links in https://cdat-vcs.readthedocs.io/en/latest/Jupyter/Color_map_create_own.html

For example

• The link at the end of "Detailed reference document of the VCS colormap can be found at here." (at the top)
• The link in 'You can create your own colormap by using "createcolormap https://uvcdat.llnl.gov/docs/vcs/Canvas.html?highlight=createcolormap#vcs.Canvas.Canvas.createcolormap`__"