[docs minor]space for code-block (#16266)

* [docs minor]space for code-block

* correct more errors

* to runnableExamples

* add newline

Author: ringabout

compiler/astalgo.nim

@@ -222,9 +222,9 @@ proc getNamedParamFromList*(list: PNode, ident: PIdent): PSym =
   ## gensym'ed and then they have '\`<number>' suffix that we need to
   ## ignore, see compiler / evaltempl.nim, snippet:
   ##
-  ##..code-block:: nim
+  ## .. code-block:: nim
   ##
-  ##    result.add newIdentNode(getIdent(c.ic, x.name.s & "\`gensym" & $x.id),
+  ##   result.add newIdentNode(getIdent(c.ic, x.name.s & "\`gensym" & $x.id),
   ##            if c.instLines: actual.info else: templ.info)
   for i in 1..<list.len:
     let it = list[i].sym

compiler/sigmatch.nim

@@ -568,9 +568,11 @@ proc inconsistentVarTypes(f, a: PType): bool {.inline.} =
 
 proc procParamTypeRel(c: var TCandidate, f, a: PType): TTypeRelation =
   ## For example we have:
-  ##..code-block:: nim
+  ## 
+  ## .. code-block:: nim
   ##   proc myMap[T,S](sIn: seq[T], f: proc(x: T): S): seq[S] = ...
   ##   proc innerProc[Q,W](q: Q): W = ...
+  ##
   ## And we want to match: myMap(@[1,2,3], innerProc)
   ## This proc (procParamTypeRel) will do the following steps in
   ## three different calls:

compiler/vmgen.nim

@@ -16,7 +16,7 @@
 #   types that use the 'node' field; the reason is that slots are
 #   re-used in a register based VM. Example:
 #
-#..code-block:: nim
+#.. code-block:: nim
 #   let s = a & b  # no matter what, create fresh node
 #   s = a & b  # no matter what, keep the node
 #

lib/pure/unidecode/unidecode.nim

@@ -52,15 +52,9 @@ proc loadUnidecodeTable*(datafile = "unidecode.dat") =
 proc unidecode*(s: string): string =
   ## Finds the sequence of ASCII characters that is the closest approximation
   ## to the UTF-8 string `s`.
-  ##
-  ## Example:
-  ##
-  ## ..code-block:: nim
-  ##
-  ##   unidecode("北京")
-  ##
-  ## Results in: "Bei Jing"
-  ##
+  runnableExamples:
+    assert unidecode("北京") == "Bei Jing "
+
   result = ""
   for r in runes(s):
     var c = int(r)