Agreed about the descriptive text.
With many many extensions out there, I generally don't bother installing anything without a proper description on the download page. This also helps make a distinction between your guides extension, and others out there.
Here is some descriptive text I've made after using your extension:
*****
Create guides quickly at any angle with incremented x,y, and even incremented steps in degrees!
Shows up under:
Extensions > Custom > Guides...
*****
Also,
You may want to add this License and Install information to your readme:
*****
License: GPL2
Installation
-----------------
Put the .inx file and .py file in ~/.config/inkscape/extensions/ and restart
inkscape.
For global installation place in /usr/share/inkscape/extensions (on
gentoo, your distro may vary)
For MS place in \Inkscape\share\extensions\
Extension appears under Extensions > Render > Guides Creator...
*****
-C