Rephrase contribution guidelines, fix typos

contributing.md

@@ -9,9 +9,9 @@ Our goal is to have a list of things that anybody would have to learn if they we
 
 Your contributions to this repo are always welcome!
 Bear in mind, that this repo is *highly opinionated*, *unbiased* and *curated*.
-Your opinion on value of any resource may not match the opinion of curator.
+Your opinion on value of any resource may not match the opinion of the curators.
 
-**No PR will be discarded without explanations!**
+**No PR will be discarded without explanation!**
 
 ## How are these roadmaps made?
 
@@ -23,12 +23,12 @@ Your opinion on value of any resource may not match the opinion of curator.
 * Export the xml file `File > Export as > XML > uncheck "compressed" > Export` and put it in the `images` directory
 * Export the svg file `File > Export as > SVG > uncheck "Include a copy of my diagram" > Export` and put it in the `images` directory
 * Make sure that the width and height of the SVG match the actual image content to avoid unnecessary whitespace around the image
-* Commits your changes and open a PR
+* Commit your changes and open a PR
 
 ## Guidelines
 
 * **Adding everything available out there is not the goal!**  
-The roadmaps represents the skillset most valuable today i.e. if you were to enter any of the listed fields today, what would you learn! There might be things that are of-course being used today but prioritize the things that are most in demand today. Use your critical thinking to filter out non-essential stuff. Give honest arguments for why the resource should be included.
+The roadmaps represent the skillset most valuable in present time meaning that if you were to enter any of the listed fields today, that's what you would learn first. Although there is an endless amount of techniques, tools and components that were important in the past or appear promising to become relevant in the future, prioritize the skills that are generally most relevant for today's demand. Use your critical thinking to filter out non-essential stuff. Give honest arguments for why the resource should be included.
 * **One item per Pull Request**  
 There may be a discussion related to an item you want to add. Adding just a single item per pull request makes it much easier for everyone involved.
 * Write meaningful commit messages