Grammar changes

There were a few grammatical mistakes and one spelling error in
the various .md files, so I fixed them :)
Signed-off-by: Kewbish <kewbish@gmail.com>

.github/BUILD.md

@@ -1,4 +1,4 @@
-# Umbraco Cms Build
+# Umbraco CMS Build
 
 ## Are you sure?
 
@@ -66,7 +66,7 @@ The Visual Studio object is `null` when Visual Studio has not been detected (eg
 * `Path`: Visual Studio installation path (eg some place under `Program Files`)
 * `Major`: Visual Studio major version (eg `15` for VS 2017)
 * `Minor`: Visual Studio minor version
-* `MsBUild`: the absolute path to the MsBuild executable
+* `MsBuild`: the absolute path to the MsBuild executable
 
 #### GetUmbracoVersion
 

.github/CODE_OF_CONDUCT.md

@@ -29,4 +29,4 @@ Don't rest on your laurels and never accept the status quo. Contribute and give
 
 ## Friendly
 
-Don’t judge upon mistakes made but rather upon the speed and quality with which mistakes are corrected. Friendly posts and contributions generate smiles and builds long lasting relationships.
+Don’t judge upon mistakes made but rather upon the speed and quality with which mistakes are corrected. Friendly posts and contributions generate smiles and build long lasting relationships.

.github/CONTRIBUTING.md

@@ -38,7 +38,7 @@ This document gives you a quick overview on how to get started.
 
 ### Guidelines for contributions we welcome
 
-Not all changes are wanted, so on occassion we might close a PR without merging it. We will give you feedback why we can't accept your changes and we'll be nice about it, thanking you for spending your valuable time.
+Not all changes are wanted, so on occasion we might close a PR without merging it. We will give you feedback why we can't accept your changes and we'll be nice about it, thanking you for spending your valuable time.
 
 We have [documented what we consider small and large changes](CONTRIBUTION_GUIDELINES.md). Make sure to talk to us before making large changes.
 

.github/CONTRIBUTION_GUIDELINES.md

@@ -13,7 +13,7 @@ We’re usually able to handle small PRs pretty quickly. A community volunteer w
 
 Umbraco HQ will regularly mark newly created issues on the issue tracker with the `Up for grabs` tag. This means that the proposed changes are wanted in Umbraco but the HQ does not have the time to make them at this time. We encourage anyone to pick them up and help out.
 
-If you do start working on something, make sure leave a small comment on the issue saying something like: "I'm working on this". That way other people stumbling upon the issue know they don't need to pick it up, someone already has.
+If you do start working on something, make sure to leave a small comment on the issue saying something like: "I'm working on this". That way other people stumbling upon the issue know they don't need to pick it up, someone already has.
 
 ## Large PRs
 New features and large refactorings - can be recognized by seeing a large number of changes, plenty of new files, updates to package manager files (NuGet’s packages.config, NPM’s packages.json, etc.).  
@@ -30,6 +30,6 @@ It is highly recommended that you speak to the HQ before making large, complex c
 
 ### Pull request or package?
 
-If it doesn’t fit in CMS right now, we will likely encourage you to make it into a package instead. A package is a great way to check out popularity of a feature, learn how people use it, validate good usability and to fix bugs.  
+If it doesn’t fit in CMS right now, we will likely encourage you to make it into a package instead. A package is a great way to check out popularity of a feature, learn how people use it, validate good usability and fix bugs.  
 
 Eventually, a package could "graduate" to be included in the CMS.