I think you're doing pretty good in terms of attracting people to your project but, to use startup terms, there is no project-market fit.
It's a tool for people who can write their own recipes and are comfortable running a unix service.
There's a very small number of people who are even capable of using such tool.
On top of that, the value is too low. I'm capable of setting this up but I don't care enough about being e-mailed about Github API release notification (or other scenarios in your docs) to go through the hassle.
As far as constructive feedback goes. If you want to make your project more useful:
* focus on recipes. Each new recipe is potentially additional marketing. Make recipes more prominent in your docs
* make a publicly available instance where people can create accounts and use it without self-hosting. Maybe there's even a business there
* more notification options (Slack seems like a no-brainer). Or even turn it into IFTTT-like system
* keep writing more posts, blogging, using twitter, posting to HN etc. Those are valid marketing tools, just don't expect miracles.
I would still not get your hopes up. You might end up doing a lot of work and still not have a product-market fit.
However, I will say I think there's probably not much "market" for your app. It seems like it's just a wrapper for what can already be done with webhooks and slack.