examples: use markdown hyperlinks

[Akim Demaille]

commit 11b5bac7bfc096f7ba3ad05c03c2e8c1f1187d30
Author: Akim Demaille <address@hidden>
Date:   Sun May 10 11:30:31 2020 +0200

    examples: use markdown hyperlinks
    
    * examples/c++/README.md, examples/c++/calc++/README.md,
    * examples/c/README.md: here.

diff --git a/examples/c++/README.md b/examples/c++/README.md
index 78e643e3..cbef0021 100644
--- a/examples/c++/README.md
+++ b/examples/c++/README.md
@@ -13,8 +13,8 @@ semantic value.
 
 Run as `./simple`.
 
-Extracted from the documentation: "A Simple C++ Example".
-https://www.gnu.org/software/bison/manual/html_node/A-Simple-C_002b_002b-Example.html
+Extracted from the documentation: [A Simple C++
+Example](https://www.gnu.org/software/bison/manual/html_node/A-Simple-C_002b_002b-Example.html).
 
 ## variant.yy - Self-contained example in C++98
 A variation of simple.yy, in C++98.
@@ -36,8 +36,8 @@ starting point for a clean parser in C++.  The previous 
examples are better
 introductory examples, and the C examples are also useful introductory
 examples.
 
-Extracted from the documentation: "A Complete C++ Example".
-https://www.gnu.org/software/bison/manual/html_node/A-Complete-C_002b_002b-Example.html
+Extracted from the documentation: [A Complete C++
+Example](https://www.gnu.org/software/bison/manual/html_node/A-Complete-C_002b_002b-Example.html).
 
 <!---
 
diff --git a/examples/c++/calc++/README.md b/examples/c++/calc++/README.md
index 1a6a8722..2c0a8363 100644
--- a/examples/c++/calc++/README.md
+++ b/examples/c++/calc++/README.md
@@ -5,9 +5,9 @@ saw the traditional implementation in C, please first read
 examples/c/lexcalc, which can be seen as a C precursor of this example.
 
 Read the corresponding chapter in the documentation: "A Complete C++
-Example".  It is also available on line (maybe with a different version of
-Bison):
-https://www.gnu.org/software/bison/manual/html_node/A-Complete-C_002b_002b-Example.html
+Example".  It is also available [on
+line](https://www.gnu.org/software/bison/manual/html_node/A-Complete-C_002b_002b-Example.html)
+(maybe with a different version of Bison).
 
 To use it, copy this directory into some work directory, and run `make` to
 compile the executable, and try it.  It is a simple calculator which accepts
diff --git a/examples/c/README.md b/examples/c/README.md
index 2eb60449..7d2cb2ac 100644
--- a/examples/c/README.md
+++ b/examples/c/README.md
@@ -10,8 +10,8 @@ The first example is that of a simple double-precision 
Reverse Polish
 Notation calculator (a calculator using postfix operators). This example
 provides a good starting point, since operator precedence is not an issue.
 
-Extracted from the documentation: "Reverse Polish Notation Calculator"
-https://www.gnu.org/software/bison/manual/html_node/RPN-Calc.html
+Extracted from the documentation: [Reverse Polish Notation
+Calculator](https://www.gnu.org/software/bison/manual/html_node/RPN-Calc.html).
 
 ## calc - Simple Calculator
 This example is slightly more complex than rpcalc: it features infix
@@ -24,8 +24,8 @@ A more complete C example: a multi-function calculator.  More 
complex than
 the previous example.  Using precedence directives to support infix
 operators.
 
-Extracted from the documentation: "Multi-Function Calculator: mfcalc".
-https://www.gnu.org/software/bison/manual/html_node/Multi_002dfunction-Calc.html
+Extracted from the documentation: [Multi-Function Calculator:
+mfcalc](https://www.gnu.org/software/bison/manual/html_node/Multi_002dfunction-Calc.html).
 
 ## lexcalc - calculator with Flex and Bison
 The calculator with precedence directives and location tracking.  It uses