Spelling (#870)

* spelling: differently

* spelling: irrelevant

* spelling: specified

docs/Strings.md

 # Encodings and `yaml-cpp` #
 
-`yaml-cpp` will parse any file as specificed by the [YAML 1.2 spec](http://www.yaml.org/spec/1.2/spec.html#id2570322). Internally, it stores all strings in UTF-8, and representation is done with UTF-8. This means that in
+`yaml-cpp` will parse any file as specified by the [YAML 1.2 spec](http://www.yaml.org/spec/1.2/spec.html#id2570322). Internally, it stores all strings in UTF-8, and representation is done with UTF-8. This means that in
 
 ```
 std::string str;

src/scanner.cpp

@@ -88,7 +88,7 @@ void Scanner::ScanNextToken() {
     return StartStream();
   }
 
-  // get rid of whitespace, etc. (in between tokens it should be irrelevent)
+  // get rid of whitespace, etc. (in between tokens it should be irrelevant)
   ScanToNextToken();
 
   // maybe need to end some blocks

src/scantoken.cpp

@@ -171,7 +171,7 @@ void Scanner::ScanBlockEntry() {
 
 // Key
 void Scanner::ScanKey() {
-  // handle keys diffently in the block context (and manage indents)
+  // handle keys differently in the block context (and manage indents)
   if (InBlockContext()) {
     if (!m_simpleKeyAllowed)
       throw ParserException(INPUT.mark(), ErrorMsg::MAP_KEY);
@@ -199,7 +199,7 @@ void Scanner::ScanValue() {
     // seems fine)
     m_simpleKeyAllowed = false;
   } else {
-    // handle values diffently in the block context (and manage indents)
+    // handle values differently in the block context (and manage indents)
     if (InBlockContext()) {
       if (!m_simpleKeyAllowed)
         throw ParserException(INPUT.mark(), ErrorMsg::MAP_VALUE);