Minor doc fixes; follow up to 17258 and 17259 (#18123)

Co-authored-by: quantimnot <[email protected]>

Author: quantimnot

doc/manual.rst

@@ -363,7 +363,7 @@ contain the following `escape sequences`:idx:\ :
   ``\\``                   `backslash`:idx:
   ``\"``                   `quotation mark`:idx:
   ``\'``                   `apostrophe`:idx:
-  ``\\`` '0'..'9'+         `character with decimal value d`:idx:;
+  ``\`` '0'..'9'+         `character with decimal value d`:idx:;
                            all decimal digits directly
                            following are used for the character
   ``\a``                   `alert`:idx:
@@ -473,7 +473,7 @@ literals:
   ``\\``                   `backslash`:idx:
   ``\"``                   `quotation mark`:idx:
   ``\'``                   `apostrophe`:idx:
-  ``\\`` '0'..'9'+         `character with decimal value d`:idx:;
+  ``\`` '0'..'9'+          `character with decimal value d`:idx:;
                            all decimal digits directly
                            following are used for the character
   ``\a``                   `alert`:idx:
@@ -7825,7 +7825,7 @@ Threads
 
 To enable thread support the `--threads:on`:option: command-line switch needs to
 be used. The system_ module then contains several threading primitives.
-See the `threads <threads.html>`_ and `channels <channels.html>`_ modules
+See the `threads <threads.html>`_ and `channels <channels_builtin.html>`_ modules
 for the low-level thread API. There are also high-level parallelism constructs
 available. See `spawn <manual_experimental.html#parallel-amp-spawn>`_ for
 further details.

doc/manual_experimental_strictnotnil.rst

@@ -143,7 +143,7 @@ Merging usually merges maps and alias sets: nilabilities are merged like this:
     else:
       MaybeNil
 
-Special handling is for `.isNil` and ` == nil`, also for `not`, `and` and `or`.
+Special handling is for `.isNil` and `== nil`, also for `not`, `and` and `or`.
 
 `not` reverses the nilability, `and` is similar to "forking" : the right expression is checked in the layer resulting from the left one and `or` is similar to "merging": the right and left expression should be both checked in the original layer.
 

doc/tut1.rst

@@ -114,7 +114,7 @@ String and character literals
 -----------------------------
 
 String literals are enclosed in double-quotes; character literals in single
-quotes. Special characters are escaped with ``\\``: ``\n`` means newline, ``\t``
+quotes. Special characters are escaped with ``\``: ``\n`` means newline, ``\t``
 means tabulator, etc. There are also *raw* string literals:
 
 .. code-block:: Nim