[DOC] Enhanced RDoc for String (#5730)

Treats:

    #start_with?
    #end_with?
    #delete_prefix
    #delete_prefix!
    #delete_suffix
    #delete_suffix!

4 files changed, 45 insertions, 0 deletions

diff --git a/doc/string/delete_prefix.rdoc b/doc/string/delete_prefix.rdoc
new file mode 100644
index 0000000000..fa9d8abd38
--- /dev/null
+++ b/doc/string/delete_prefix.rdoc
@@ -0,0 +1,8 @@
+Returns a copy of +self+ with leading substring <tt>prefix</tt> removed:
+
+  'hello'.delete_prefix('hel')      # => "lo"
+  'hello'.delete_prefix('llo')      # => "hello"
+  'тест'.delete_prefix('те')        # => "ст"
+  'こんにちは'.delete_prefix('こん')  # => "にちは"
+
+Related: String#delete_prefix!, String#delete_suffix.
diff --git a/doc/string/delete_suffix.rdoc b/doc/string/delete_suffix.rdoc
new file mode 100644
index 0000000000..4862b725cf
--- /dev/null
+++ b/doc/string/delete_suffix.rdoc
@@ -0,0 +1,8 @@
+Returns a copy of +self+ with trailing substring <tt>suffix</tt> removed:
+
+  'hello'.delete_suffix('llo')      # => "he"
+  'hello'.delete_suffix('hel')      # => "hello"
+  'тест'.delete_suffix('ст')        # => "те"
+  'こんにちは'.delete_suffix('ちは')  # => "こんに"
+
+Related: String#delete_suffix!, String#delete_prefix.
diff --git a/doc/string/end_with_p.rdoc b/doc/string/end_with_p.rdoc
new file mode 100644
index 0000000000..f959cf7aaa
--- /dev/null
+++ b/doc/string/end_with_p.rdoc
@@ -0,0 +1,11 @@
+Returns whether +self+ ends with any of the given +strings+.
+
+Returns +true+ if any given string matches the end, +false+ otherwise:
+
+  'hello'.end_with?('ello')               #=> true
+  'hello'.end_with?('heaven', 'ello')     #=> true
+  'hello'.end_with?('heaven', 'paradise') #=> false
+  'тест'.end_with?('т')                   # => true
+  'こんにちは'.end_with?('は')              # => true
+
+Related: String#start_with?.
diff --git a/doc/string/start_with_p.rdoc b/doc/string/start_with_p.rdoc
new file mode 100644
index 0000000000..1cfed76296
--- /dev/null
+++ b/doc/string/start_with_p.rdoc
@@ -0,0 +1,18 @@
+Returns whether +self+ starts with any of the given +string_or_regexp+.
+
+Matches patterns against the beginning of+self+.
+For each given +string_or_regexp+, the pattern is:
+
+- +string_or_regexp+ itself, if it is a Regexp.
+- <tt>Regexp.quote(string_or_regexp)</tt>, if +string_or_regexp+ is a string.
+
+Returns +true+ if any pattern matches the beginning, +false+ otherwise:
+
+  'hello'.start_with?('hell')               # => true
+  'hello'.start_with?(/H/i)                 # => true
+  'hello'.start_with?('heaven', 'hell')     # => true
+  'hello'.start_with?('heaven', 'paradise') # => false
+  'тест'.start_with?('т')                   # => true
+  'こんにちは'.start_with?('こ')              # => true
+
+Related: String#end_with?.