Update documentation text

Summary:
The word 'english' has several issues:
 - the whole documentation and source code is in English,
   there is no point in mentioning here specifically
 - the character 'E' needs to be capitalized, as in
   Ecore, Evas, Elementary

Reviewers: zmike, herdsman

Subscribers: cedric, seoz, jpeg

Differential Revision: https://phab.enlightenment.org/D3740

src/lib/evas/Evas_Common.h

@@ -5055,7 +5055,7 @@ EAPI void        evas_cserve_disconnect(void);
 
 /**
  * Converts the given Evas image load error code into a string
- * describing it in english.
+ * describing it in human-readable text.
  *
  * @param error the error code, a value in ::Evas_Load_Error.
  * @return Always returns a valid string. If the given @p error is not