Fix many broken links and prefer relative links within docs (#12463)

* Fix many broken links

Note that contrary to what docgen.rst currently says, the ids have
to match exactly or else most web browsers will not jump to the
intended symbol.

* Prefer relative links for Nim documentation

This is more friendly to those browsing the documentation without
a network connection. The nim-doc package in Debian allows this,
for example.

Also, the domain name being used was not consistent. It could have
been either nim-lang.org or nim-lang.github.io, and those reading
the stable docs could have found themselves suddenly reading the
devel docs instead.

* koch.rst: remove link to nonexistent section

* manual.rst: remove unintended link

cast[T](0) is interpreted as a link to id 0 with text T, so escape
the opening parentheses to display the intended output.

* asyncstreams: replace unintended link with emphasis

* Fix word wrapping

1 files changed, 3 insertions, 2 deletions

diff --git a/lib/pure/collections/tables.nim b/lib/pure/collections/tables.nim
index 3c91ba9c7..7d1633e7d 100644
--- a/lib/pure/collections/tables.nim
+++ b/lib/pure/collections/tables.nim
@@ -134,7 +134,8 @@
 ##   # 'a': 5, 'b': 2, 'c': 1, 'd': 1, 'r': 2}
 ##
 ## The same could have been achieved by manually iterating over a container
-## and increasing each key's value with `inc proc<#inc,CountTable[A],A,int>`_:
+## and increasing each key's value with `inc proc
+## <#inc,CountTable[A],A,Positive>`_:
 ##
 ## .. code-block::
 ##   import tables
@@ -2236,7 +2237,7 @@ proc `[]=`*[A](t: var CountTable[A], key: A, val: int) =
   ##
   ## See also:
   ## * `[] proc<#[],CountTable[A],A>`_ for retrieving a value of a key
-  ## * `inc proc<#inc,CountTable[A],A,int>`_ for incrementing a
+  ## * `inc proc<#inc,CountTable[A],A,Positive>`_ for incrementing a
   ##   value of a key
   assert(not t.isSorted, "CountTable must not be used after sorting")
   assert val >= 0