RFR: 8273001: Improve the doclet.usage.tagletpath option description

[Pavel Rappo]

Please review this PR to clarify javadoc help output. The net effect of this change can be seen when comparing the relevant excerpts from before and after output.

Before:

    ...
    --snippet-path <path>
                  The path for external snippets
    -sourcetab <tab length>
                  Specify the number of spaces each tab takes up in the source
    -splitindex   Split index into one file per letter
    -tag <name>:<locations>:<header>
                  Specify single argument custom tags
    -taglet       The fully qualified name of Taglet to register
    -tagletpath   The path to Taglets
    ...


After:

    ...
    --snippet-path <path>
                  The path to external snippets
    -sourcetab <tab length>
                  Specify the number of spaces each tab takes up in the source
    -splitindex   Split index into one file per letter
    -tag <name>:<locations>:<header>
                  Specify single argument custom tags
    -taglet       The fully qualified name of taglet to register
    -tagletpath <path>
                  The path to custom taglets
    ...


I'm not a grammarian, but:

  * "To" seems more appropriate than "for" in this context.
  * There's no reason to use title-cased "Taglet(s)". At least there's no more reason for this than there is for "Doclet(s)", which is consistently spelled as "doclet(s)" (except for where it starts a sentence).

-------------

Commit messages:
 - Initial commit

Changes: https://git.openjdk.java.net/jdk/pull/6745/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6745&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8273001
  Stats: 10 lines in 2 files changed: 3 ins; 0 del; 7 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6745.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6745/head:pull/6745

PR: https://git.openjdk.java.net/jdk/pull/6745