docs($sce): correct typos

Line 548: Remove duplicate 'not' and clarify wording
Line 556: Remove period within parenthetical statement
Line 560: Clarify wording
Line 570: Capitalize 'E.g.' at the start of a sentence

Closes angular#12252

src/ng/sce.js

@@ -545,19 +545,19 @@ function $SceDelegateProvider() {
  *      characters: '`:`', '`/`', '`.`', '`?`', '`&`' and ';'.  It's a useful wildcard for use
  *      in a whitelist.
  *    - `**`: matches zero or more occurrences of *any* character.  As such, it's not
- *      not appropriate to use in for a scheme, domain, etc. as it would match too much.  (e.g.
+ *      appropriate for use in a scheme, domain, etc. as it would match too much.  (e.g.
  *      http://**.example.com/ would match http://evil.com/?ignore=.example.com/ and that might
  *      not have been the intention.)  Its usage at the very end of the path is ok.  (e.g.
  *      http://foo.example.com/templates/**).
  *  - **RegExp** (*see caveat below*)
  *    - *Caveat*:  While regular expressions are powerful and offer great flexibility,  their syntax
  *      (and all the inevitable escaping) makes them *harder to maintain*.  It's easy to
  *      accidentally introduce a bug when one updates a complex expression (imho, all regexes should
- *      have good test coverage.).  For instance, the use of `.` in the regex is correct only in a
+ *      have good test coverage).  For instance, the use of `.` in the regex is correct only in a
  *      small number of cases.  A `.` character in the regex used when matching the scheme or a
  *      subdomain could be matched against a `:` or literal `.` that was likely not intended.   It
  *      is highly recommended to use the string patterns and only fall back to regular expressions
- *      if they as a last resort.
+ *      as a last resort.
  *    - The regular expression must be an instance of RegExp (i.e. not a string.)  It is
  *      matched against the **entire** *normalized / absolute URL* of the resource being tested
  *      (even when the RegExp did not have the `^` and `$` codes.)  In addition, any flags
@@ -567,7 +567,7 @@ function $SceDelegateProvider() {
  *      remember to escape your regular expression (and be aware that you might need more than
  *      one level of escaping depending on your templating engine and the way you interpolated
  *      the value.)  Do make use of your platform's escaping mechanism as it might be good
- *      enough before coding your own.  e.g. Ruby has
+ *      enough before coding your own.  E.g. Ruby has
  *      [Regexp.escape(str)](http://www.ruby-doc.org/core-2.0.0/Regexp.html#method-c-escape)
  *      and Python has [re.escape](http://docs.python.org/library/re.html#re.escape).
  *      Javascript lacks a similar built in function for escaping.  Take a look at Google