feat(docs): various improvements

- removing spaces at end of line
- fixing spelling and grammar mistakes
- making sure 'Vikunja' is spelled the same way everywhere
- prefer using editors word wrap instead of hardcoding word wrap in markdown (reason: different word wrap per editor & end of line space)
- add newline add end where missing
- remove double colon at end of headlines
- remove unnecessary indention
- make sure code blocks and headlines etc always have an empty line around

docs/content/doc/development/errors.md

@@ -13,14 +13,14 @@ menu:
 All custom errors are defined in `pkg/models/errors.go`.
 You should add new ones in this file.
 
-Custom errors usually have fields for the http return code, a [vikunja-specific error code]({{< ref "../usage/errors.md">}}) 
+Custom errors usually have fields for the http return code, a [Vikunja-specific error code]({{< ref "../usage/errors.md">}}) 
 and a human-readable error message about what went wrong.
 
 An error consists of multiple functions and definitions:
 
 {{< highlight golang >}}
 // This struct holds any information about this specific error.
-// In this case, it contains the user ID of a nonexistand user.
+// In this case, it contains the user ID of a nonexistent user.
 // This type should always be a struct, even if it has no values in it.
 
 // ErrUserDoesNotExist represents a "UserDoesNotExist" kind of error.
@@ -44,21 +44,21 @@ func (err ErrUserDoesNotExist) Error() string {
 	return fmt.Sprintf("User does not exist [user id: %d]", err.UserID)
 }
 
-// This const holds the vikunja error code used to be able to identify this error without having to 
+// This const holds the Vikunja error code used to be able to identify this error without having to 
 // rely on an error string.
 // This needs to be unique, so you should check whether the error code exists or not.
 // The general convention for error codes is as follows:
 // * Every "group" errors lives in a thousend something. For example all user issues are 1000-something, all 
 //   project errors are 3000-something and so on.
 // * New error codes should be the current max error code + 1. Don't take free numbers to prevent old errors
-//   which are depricated and removed from being "new ones". For example, if there are error codes 1001, 1002, 1004,
+//   which are deprecated and removed from being "new ones". For example, if there are error codes 1001, 1002, 1004,
 //   a new error should be 1005 and not 1003.
 
 // ErrCodeUserDoesNotExist holds the unique world-error code of this error
 const ErrCodeUserDoesNotExist = 1005
 
 // This is the implementation which returns an http error which is then passed to the client.
-// Here you define the http status code with which one the error will be returned, the vikunja error code and 
+// Here you define the http status code with which one the error will be returned, the Vikunja error code and 
 // a human-readable error message.
 
 // HTTPError holds the http error description