Fix the syntax that is weird as markdown from README

We intend to browse this on GitHub too, so we shouldn't use the RDoc
syntax that doesn't look clean on GitHub.

Even if "ERB" is linked to the ERB module, it's still not the end of the
world.

Author: k0kubun

README.md

@@ -1,21 +1,21 @@
-# \ERB (Embedded Ruby)
+# ERB (Embedded Ruby)
 
-\ERB is an easy-to-use, but also very powerful, [template processor][template processor].
+ERB is an easy-to-use, but also very powerful, [template processor][template processor].
 
-\ERB is commonly used to produce:
+ERB is commonly used to produce:
 
 - Customized or personalized email messages.
 - Customized or personalized web pages.
 - Software code (in code-generating applications).
 
-Like method [sprintf][sprintf], \ERB can format run-time data into a string.
-\ERB, however, is *much more powerful*
+Like method [sprintf][sprintf], ERB can format run-time data into a string.
+ERB, however, is *much more powerful*
 
-## How \ERB Works
+## How ERB Works
 
-Using \ERB, you can create a *template*: a plain-text string that has specially-formatted *tags*,
-then store it into an \ERB object;
-when \ERB produces _result_ string, it:
+Using ERB, you can create a *template*: a plain-text string that has specially-formatted *tags*,
+then store it into an ERB object;
+when ERB produces _result_ string, it:
 
 - Inserts run-time-evaluated expressions into the result.
 - Executes snippets of Ruby code.
@@ -35,7 +35,7 @@ There are three types of tags:
 | Execution tag  |     <tt>'<% _ruby_code_ %>'</tt>     |     Execute <tt>_ruby_code_</tt>.     |        None.         |                 
 | Comment tag    |   <tt>'<%# _comment_text_ %>'</tt>   |                 None.                 |        None.         |
 
-These examples use `erb`, the \ERB command-line interface;
+These examples use `erb`, the ERB command-line interface;
 each "echoes" a string template and pipes it to `erb` as input:
 
 
@@ -56,16 +56,16 @@ each "echoes" a string template and pipes it to `erb` as input:
         echo "<%# TODO: Fix this nonsense. %> Nonsense." | erb
         " Nonsense."
 
-## How to Use \ERB
+## How to Use ERB
 
-You can use \ERB either:
+You can use ERB either:
 
 - In a program: see class ERB.
 - From the command line: see [ERB Executable][erb executable].
 
 ## Installation
 
-\ERB is installed with Ruby, and so there's no further installation needed.
+ERB is installed with Ruby, and so there's no further installation needed.
 
 ## Other Template Engines
 
@@ -77,7 +77,7 @@ Other popular template engines may be found in the [Ruby Toolbox][ruby toolbox].
 
 ## Code
 
-The \ERB source code is in GitHub project [ruby/erb][ruby/erb]/
+The ERB source code is in GitHub project [ruby/erb][ruby/erb].
 
 ## Bugs