doc(jsdoc): Fix JSDocs violations and typo (#463)

* Fix typo.

* Fix JSDocs error.

src/js/editor/post.js

@@ -371,7 +371,7 @@ class PostEditor {
    *     // section has text of "Howdy"
    *
    * @param {Position} position The position to delete at
-   * @param {direction=DIRECTION.BACKWARD} direction The direction to delete in
+   * @param {Direction} [direction=DIRECTION.BACKWARD] direction The direction to delete in
    * @param {Object} [options]
    * @param {String} [options.unit="char"] The unit of deletion ("word" or "char")
    * @return {Position}

src/js/parsers/text.js

@@ -16,7 +16,7 @@ const CR_LF_REGEX = new RegExp(CR+LF, 'g');
 
 export const SECTION_BREAK = LF;
 
-function normalizeLindEndings(text) {
+function normalizeLineEndings(text) {
   return text.replace(CR_LF_REGEX, LF)
              .replace(CR_REGEX, LF);
 }
@@ -35,7 +35,7 @@ export default class TextParser {
    * @return {Post} a post abstract
    */
   parse(text) {
-    text = normalizeLindEndings(text);
+    text = normalizeLineEndings(text);
     text.split(SECTION_BREAK).forEach(text => {
       let section = this._parseSection(text);
       this._appendSection(section);

src/js/utils/cursor/position.js

@@ -106,7 +106,7 @@ Position = class Position {
   /**
    * Returns a range from this position to the given tail. If no explicit
    * tail is given this returns a collapsed range focused on this position.
-   * @param {Position=this} tail The ending position
+   * @param {Position} [tail=this] The ending position
    * @return {Range}
    * @public
    */