Merge pull request #4511 from oderwat/doc-changes1

Small changes to the docs to make it easier to find stuff.

lib/pure/os.nim

@@ -336,7 +336,7 @@ proc setCurrentDir*(newDir: string) {.inline, tags: [].} =
 
 proc expandFilename*(filename: string): string {.rtl, extern: "nos$1",
   tags: [ReadDirEffect].} =
-  ## Returns the full path of `filename`, raises OSError in case of an error.
+  ## Returns the full (`absolute`:idx:) path of the file `filename`, raises OSError in case of an error.
   when defined(windows):
     const bufsize = 3072'i32
     when useWinUnicode:

lib/system.nim

@@ -3359,7 +3359,11 @@ proc astToStr*[T](x: T): string {.magic: "AstToStr", noSideEffect.}
 
 proc instantiationInfo*(index = -1, fullPaths = false): tuple[
   filename: string, line: int] {. magic: "InstantiationInfo", noSideEffect.}
-  ## provides access to the compiler's instantiation stack line information.
+  ## provides access to the compiler's instantiation stack line information
+  ## of a template.
+  ##
+  ## While similar to the `caller info`:idx: of other languages, it is determined
+  ## at compile time.
   ##
   ## This proc is mostly useful for meta programming (eg. ``assert`` template)
   ## to retrieve information about the current filename and line number.