fixes typos in javadoc comments

Readme.html

 
 <h2>Changes</h2>
 
-<p>-version 3.21 on October 3, 2016
+<p>-version 3.21 on October 4, 2016
 <ul>
 <li>JIRA JASSIST-244, 245, 248, 250, 255, 256, 259, 262.
 <li><code>javassist.tools.Callback</code> was modified to be Java 1.4 compatible.

src/main/javassist/CtField.java

      * this field.  They have to be explicitly updated.  For example,
      * if some method contains an expression {@code t.value} and the type
      * of the variable {@code t} is changed by {@link #setType(CtClass)}
-     * from {@code int} to {@code double}, then {@ t.value} has to be modified
-     * since the bytecode of {@code t.value} contains the type information.
+     * from {@code int} to {@code double}, then {@code t.value} has to be modified
+     * as well since the bytecode of {@code t.value} contains the type information.
      * </p>
      *
      * @see CodeConverter

src/main/javassist/bytecode/ClassFile.java

      * returns null if the specified attributed is not found.
      *
      * <p>An attribute name can be obtained by, for example,
-     * {@link AnnotationsAttribute#visibleTab} or
-     * {@link AnnotationsAttribute#invisibleTab}. 
+     * {@link AnnotationsAttribute#visibleTag} or
+     * {@link AnnotationsAttribute#invisibleTag}. 
      * </p>
      * 
      * @param name          attribute name

src/main/javassist/bytecode/FieldInfo.java

      * It returns null if the specified attribute is not found.
      *
      * <p>An attribute name can be obtained by, for example,
-     * {@link AnnotationsAttribute#visibleTab} or
-     * {@link AnnotationsAttribute#invisibleTab}. 
+     * {@link AnnotationsAttribute#visibleTag} or
+     * {@link AnnotationsAttribute#invisibleTag}. 
      * </p>
      * 
      * @param name      attribute name

src/main/javassist/bytecode/MethodInfo.java

      * method returns null.
      * 
      * <p>An attribute name can be obtained by, for example,
-     * {@link AnnotationsAttribute#visibleTab} or
-     * {@link AnnotationsAttribute#invisibleTab}.
+     * {@link AnnotationsAttribute#visibleTag} or
+     * {@link AnnotationsAttribute#invisibleTag}.
      * </p>
      * 
      * @param name attribute name